Question

Eliza's backpack weighs 18 and StartFraction 7 over 9 EndFraction pounds with her math book in it. Without her math book, her backpack weighs 14 and StartFraction 7 over 8 EndFraction pounds. How much does Eliza's math book weigh? 3 and StartFraction 11 over 72 EndFraction pounds 3 and StartFraction 65 over 72 EndFraction pounds 4 and StartFraction 11 over 72 EndFraction pounds 4 and StartFraction 65 over 72 EndFraction pounds

Answer 1

`Math\ Book = 3(65)/(72)\ kg`

Explanation:

Given

`Backpack = 18(7)/(9)kg` --- with math book

`Backpack = 14(7)/(8)kg` --- without math book

Required

Determine the weight of her math book

To do this, we simply calculate the difference in the weights given.

Math Book= Backpack(with math book) - Backpack (without math book)

`Math\ Book = 18(7)/(9) - 14(7)/(8)`

`Math\ Book = (169)/(9) - (119)/(8)`

Take LCM

`Math\ Book = (8 * 169 - 9 * 119)/(72)`

`Math\ Book = (1352 - 1071)/(72)`

`Math\ Book = (281)/(72)`

`Math\ Book = 3(65)/(72)\ kg`