Algebra.

227. ANOTHER METHOD OF FINDING TWO NUMBERS WHEN THEIR SUM AND DIFFERENCE ARE GIVEN.

1. The difference of two numbers is 17 and their sum is 69. What are the numbers?

2. The difference of two numbers is 8.4 and their sum 75.6. What are the numbers?

3. The difference of two numbers is d and their sum is s. What are the numbers?

Observe that any number you please may be put in the place of s and any number less than s in the place of d; so when the sum and difference of two numbers are given the larger may be found by adding the difference to the sum and dividing the amount by 2.

4. A horse and a harness together are worth $146, and the horse is worth $74 more than the harness. Find the value of each.

Geometry.

228. HOW MANY DEGREES IN EACH ANGLE OF A REGULAR PENTAGON?

2. The sum of the angles of one triangle is equal to

right angles; then the sum of the angles of 5 triangles is equal to right angles.

3. But the sum of the central angles in figure 2, (a+b+ c+d+e) is equal to - right angles; † then the sum of all the other angles of the five triangles is equal to 10 right angles, less 4 right angles, or 6 right angles = 540°. But the angular space that measures 540°, as shown in Figure 2, is made up of 10 equal angles, so each one of the angles is 1 tenth of 540 or 54°. Two of these angles, as 1 and 2, make one of the angles of the pentagon; therefore each angle of the pentagon measures 2 times 54° or 108°.

4. Using the protractor construct a regular pentagon as follows:

(a) Draw two lines that meet in a point, each line being 2 inches long and the angular space between them being 108°.

(b) Regarding the two lines as two sides of a regular pentagon, draw two more sides each 2 inches long and joining those already drawn at an angle of 1088.

(c) Complete the figure by drawing the fifth side and prove your work by measuring the last line drawn and the other two angles of the pentagon.

* See page 59, 6 and 7. + See page 29, Art. 66.

229. MISCELLANEOUS REVIEW.

Remembering that in speaking of the per cent of loss or gain, the cost is the base unless otherwise specified, tell the per cent of loss or gain in each of the following:

1. Bought for 2 and sold for 3.
2. Bought for 3 and sold for 2.
3. Bought for 4 and sold for 5.
4. Bought for 5 and sold for 4.
5. Bought for 5 and sold for 6.
6. Bought for 6 and sold for 5.
7. Bought for 8 and sold for 10; for 12.
8. Bought for 8 and sold for 14; for 16.
9. Bought for 8 and sold for 18; for 20.
10. Bought for 8 and sold for 4; for 2.

11. Mr. Parker sold goods at a profit of 25 %; the amount of his sales on a certain day was $24.60. How much was his profit ? *

12. Mr. Jewell sold goods at a loss of 25 %; the amount of his sales on a certain day was $24.60. How much was his loss? *

13. By selling a horse for $156 there was a loss to the seller of 20 %. What would have been his gain per cent if he had sold the horse for $234? †

14. A bill was made for wood that was supposed to be 4 feet long. It was afterwards found to be only 46 inches long. What % should be deducted from the bill?

15. The marked price on a pair of boots was 25 % above cost. If the dealer sells them for 25% less than the marked price will he receive more or less than the cost of the boots?

16. If by selling goods at a profit of 12 % a man gains $6.60, what was the cost of the goods?

$24.60 is what per cent of the cost?

+ First find the cost of the horse.

PERCENTAGE.

230. DISCOUNTING BILLS.

Many kinds of goods are usually sold "on time;" that is, the buyer may have 30, 60, or 90 days in which to pay for them. If he pays for such goods at the time of purchase or within ten days from the time of purchase, his bill is “discounted" from 1% to 6%, according to agreement; that is, a certain part of the amount of the bill is deducted from the amount.

Mr. Smith bought of amounting to $350.20. ("spot cash") was 1 %. goods?

EXAMPLE.

Marshall Field & Co. a bill of goods
The discount for immediate payment
How much must he pay for the

1% of $350.20 is $3.50. $350.20 $3.50 $346.70.

PROBLEMS.

=

"Figure the discounts" on the following bills: †

1. Bill of $324.37, discounted at 2 %.
2. Bill of $276.45, discounted at 1 %.
3. Bill of $356.50, discounted at 3 %.
4. Bill of $536.50, discounted at 6 %.
5. Bill of $561.80, discounted at 4 %.

(a) Find the sum of the five bills before they are discounted.

(b) Find the sum of the discounts.

(c) Find the sum of the five bills after discounting.

† Fractions of cents in the discount on each bill may be ignored.

Applications of Percentage.

231. DISCOUNTS FROM List Price.

Dealers in hardware, rubber boots and shoes, belting, rubber hose, and many other kinds of goods, sell from a list price agreed upon by the manufacturers. The actual price is usually less than the list price. "20% off" means that the list price is to be discounted 20%. "20 and 10 off" means that the list price is to be discounted 20%, and what remains is to be discounted 10%. Sometimes as many as nine successive discounts are allowed. Observe that in computing these the base changes with each discount.

PROBLEMS.

Find the actual cost of

1. 500 ft. -inch gas pipe, (list, 7¢ per ft.) at 50 and 10 off.

2. 350 ft. -inch gas pipe, (list, 84 per ft.) at 50 and 10 off.

3. 200 ft. 13-inch gas pipe (list, 26¢ per ft.) at 55 and 10 off.

4. 260 ft. 2-inch gas pipe (list, 35¢ per ft.) at 55 and 10 off.

5. 48-in. elbows, (list, 74 each) at 65 and 20 off.
6. 36-in. elbows, (list, 94 each) at 65 and 20 off.

(a) Find the entire cost of the six items.

7. Find the cost of 12 pairs men's rubber boots, (list, $3.00 per pair) at 25 and 10 off. Find the cost of the same at 35 off.

Why are the results unlike?

8. Which is the lower price, 50 and 10 off, or 60 off, the list being the same?

9. Bought for 40 off from list price and sold for 10 off from list price. What was my gain per cent?

10. Bought for 70 off from list and sold for 50 and 20 off from list. Did I lose or gain and how many per cent?