Question

Eliza’s backpack weighs 18 and 7/9 pounds with her math book in it. Without her math book, her backpack weighs 14 and 7/8 pounds. How much does Eliza’s math book weigh?

Answer 1

`3(65)/(72)\ pounds`

Explanation:

we know that

To find the Eliza’s math book weigh subtract the backpack weighs without the math book from the backpack weighs

First convert to an improper fractions

`18(7)/(9) =(18*9+7)/(9)=(169)/(9)`

`14(7)/(8) =(14*8+7)/(8)=(119)/(8)`

so

`(169)/(9)-(119)/(8)=(169*8-119*9)/(72)\\ \\=(281)/(72)\ pounds`

convert to a mixed number

`(281)/(72)=(216)/(72)+(65)/(72)=3(65)/(72)\ pounds`

Answer 2

18 7/9 - 14 7/8
= 169/9 - 119/8
now you must find a common denominator
= 281/72
3 65/72 lbs