Of the books in a library, 1/3 came from Robbie's collection and 15 came from Marta's. Of the rest, 15 were Elena's 1/5 were Winfield's, and 5 were purchased from the bookstore. How many book are there in the library?

Question

Dennis Khan

Mathematics

13 April, 19:29

Of the books in a library, 1/3 came from Robbie's collection and 15 came from Marta's. Of the rest, 15 were Elena's 1/5 were Winfield's, and 5 were purchased from the bookstore. How many book are there in the library?

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Answers (1)

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George Jacobs · Answer 1

Library amount: l

Robbie: r = (1/3) l

Martha: m=15

rest of books: l-r-m=e+w+b

Elena: e=15

Winfield: w=1/5 (e+w+b)

bookstore: b=5

w = (e+w+b) / 5

w = (15+5+w) / 5

w=4+w/5

(4/5) w=4

w=5

l-r-m=e+w+b

l - (1/3) l-15=15+5+5

(2/3) l=25+15

(2/3) l=40

l=60=amount of books