How many books did they donate?

Question

Anne, Bob, and Jane are pooling their books together. Anne takes 2/3 of the books, and Bob takes 20% of the remaining books. After they've taken their share, Jane takes 75% of what's left. The rest they decide to donate. If Anne took 240 books, how many did they donate?

Answer 1

We know that Anne took 240 books.

 

240 is 2/3 of what number.   Multiply 240 by 3/2 to get 360.  So there were 360 books before taking.

 

Bob takes 20% of remaining books.  That will be 0.20 multiplied by the difference of original amount and amount Anne took.  120 books remain.

 

(1/5)(120) = 24

 

Bob took 24 books.

 

 

What is left now is 360 - 240 - 24 = 96 books

 

96 books are left.   Jane takes 3/4 of this amount.

 

Jane takes (3/4)(96) = 72 books

 

 

The rest is donated. 

 

Amount donated = 360 - 240 - 24 - 72