Activity › Discussion › Math › Direct and Inverse Proportions › Reply To: Direct and Inverse Proportions
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Given :
The school librarian could buy 80 books casting Rs 90 each from the local bookseller and also given that the publisher offered her a 20% discount.
To Find:
The number of copies of Mathematics books which she could buy from the publisher for the sanctioned money.
Solution:
The cost of a Mathematics books= Rs 90
The cost of 80 Mathematics books= 80×90 = Rs 7200
The publisher offered her a 20% discount.
Then the discount on each Mathematics book= 90×(20/100)= Rs 18
Therefore after the discount cost of each book = 90-18 =Rs 72
Therefore the number of copies of Mathematics books which she could buy from the publisher for the sanctioned money = Total amount / cost of each book
=7200/72
=100
Thus the number of copies of Mathematics books is 100.