Please help with this easy fraction problem <3

18 + 7/9

14 + 7/8

First, rewrite each fraction in terms of a common denominator. 8 and 9 don't share a common multiple until 8 * 9 = 72, so we have

7/9 = (7/9) • (8/8) = (7 • 8)/(9 • 8) = 56/72

7/8 = (7/8) • (9/9) = (7 • 9)/(8 • 9) = 63/72

Next, write each whole number in terms of fractions with the same denominator. We have

18 • 72 = 1296  ==>  18 = 1296/72

14 • 72 = 1008  ==>  14 = 1008/72

Write each mixed number as an improper fraction:

18 + 7/9 = 1296/72 + 56/72 = (1296 + 56)/72 = 1352/72

14 + 7/8 = 1008/72 + 63/72 = (1008 + 63)/72 = 1071/72

If the backpack and book together weigh 18 + 7/9 pounds, and the backpack without the book weighs 14 + 7/8 pounds, then the book alone weighs the difference, call it b :

b = (18 + 7/9) - (14 + 7/8)

b = 1352/72 - 1071/72

b = (1352 - 1071)/72

b = 281/72

Convert this to a mixed number. 72 • 4 = 288, so 72 • 4 - 7 = 281:

b = (72 • 4 - 7)/72

b = (72 • 4)/72 - 7/72

b = 4 - 7/72

b = (3 + 1) - 7/72

b = 3 + (1 - 7/72)

b = 3 + 65/72