Jason bought 16 books. If the price of 1 book was $20 less than the original price, he could have bought 4 more books. What was the original price of each book?

Answer 1

(p-20)(n+4) = 16 p and n = 16
p n -20 n + 4 p - 80 = 16 p
16 p - 320 + 4 p = 80 + 16 p
4p = 400
p =100

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check
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n p = 16*100 = 1600
new p = 100 - 20 = 80
new number = 20
80 * 20 is 1600 sure enough