20%of the books in a library were fiction books while the rest were non-fiction books. When 30%of the fiction books and 15% of the non-fiction books were borrowed, there were 1312 books left in the library. How many books were borrowed?
\(total,amount=\frac{partial-amount}{corresponding-precentage}\)
total amount=1312/(1-20%*30%-80%*15%)=1312/82%=1600
How many books were borrowed?
288 books were borrowed.
