denominators over their product; thus, if it were required to find the sum of and, we should add the 3 and 7 together for a numerator, and multiply them together for a denominator, and the fraction would be . I. To subtract fractions, that have a common denominator. RULE. Subtract the less numerator from the greater, and under the remainder write the common denominator, and reduce the fraction if necessary. II. To subtract fractions whose denominators are unlike. RULE. Reduce the fractions to a common denominator, as in Addition of fractions; then write the difference of the numerators over the common denominator. 9. From take OPERATION. Ans. 4)16 12 4×4 × 3 = 48 common denominator. 4)8 12 4x2 x3 = 24 common denominator. 6X8X1=48 common denominator. 48 1x 231=231 22. From 7 take 37. Ans. 317. 23. From 8 take 5. Ans. 23. 24. From 94 take 37. Ans. 5§. 25. From 10 take 10. Ans. . III. To subtract a proper or mixed fraction from a whole number. 26. From 16 take 14. OPERATION. From 16 Take 14 142 Ans. 143. To subtract the in this example, 1 must be borrowed from the 6 in the minuend, and reduced to fourths, (), and the must be taken from them; from leaves. To pay for the 1, which was borrowed, 1 must be added to the 1 in the subtrahend, 1+1=2; and 2 taken from 16 leaves 14, and the, placed at the right hand of it, gives the answer 142. The same result will be obtained, if we adopt the following RULE. and Subtract the numerator from the denominator of the fraction, and under the remainder write the denominator, carry one to the subtrahend to be subtracted from the min uend. 13 14 17 Take 9 83. 611 If it be required to subtract one mixed number from another mixed number, the following method may be denominator of the fraction in the subtrahend, and we have a new fraction, which we write at the right hand of the other 9, thus, 91. We then multiply the numerator and denominator of the subtrahend by 7, the denominator of the minuend, and we have another new fraction, , which we place at the right hand of the other 3, thus, 3. It will now be perceived, that we have changed the fractions 92 and 33 to other fractions of the same value, having a common denominator. We now subtract as in question 26th by adding 1 (35) to i̟, which makes, and from this we subtract; thus, -=1, we then carry the 1 we borrowed to the 3, I+3=4, which we take from 9, and find 5 remaining. The answer therefore is 5. 43. From a hhd. of wine there leaked out 123 gallons, how much remained? Ans. 50ğ. 44. From $10, $24 was given to Benjamin, $31 to Lydia, $1 to Emily, and the remainder to Betsey; what did she receive ? Ans. $31. NOTE. If it be required to find the difference between two fractions, whose numerators are a unit, the most ready way will be to write the difference of the denominators over their product. 45. What is the difference between and ? Section 23. MULTIPLICATION OF VULGAR FRACTIONS. I. To multiply a fraction by a whole number, or a whole number by a fraction. Multiply the numerator of the fraction by the whole number, and under the product write the denominator of the fraction. 1. Multiply by 15. OPERATION. 7×6=105= 13 Ans. 2. Multiply by 83. This question may be analyzed as those in compound fractions. OPERATION. 11×4=2761⁄2 Ans. 3. If a man receive of a dollar for one day's labor, what will he receive for 21 days' labor? Ans. $77. 4. What cost 56lbs. of chalk at of a cent per lb. ? 5. What cost 396lbs. of copperas at Ans. $ 0.42. of a cent per lb. ? Ans. $3.24. 6. What cost 79 bushels of salt at of a dollar per bush el? 7. Multiply 376 by H. 8. Multiply by 189. Ans. $69. Ans. 243. Ans. 16617. Ans. 83. Ans. 2337. Ans. 3526. Ans. 636 II. To multiply a mixed number by a whole number, or a whole number by a mixed number. 13. Multiply 4g by 7. Ans. 32 |