SOLUTION: A bookstore currently sells 15 copies per week of a $20 book. For each $1 discount in price, the store can sell 3 more books. How many discounts will yield sales of $468 per week o

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Question 1153731: A bookstore currently sells 15 copies per week of a $20 book. For each $1 discount in price, the store can sell 3 more books. How many discounts will yield sales of $468 per week on this book? Find two solutions
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

let x be the number of $1 discounts
then price of each book is 20-x
a bookstore currently sells 15 copies, and with a discount, the store can sell 3 more books: 3x
so, the number of books sold is 15%2B3x
then
%2820-x%29%2815%2B3x%29=468
300%2B60x-15x-3x%5E2=468
300%2B45x-3x%5E2-468=0
-3x%5E2%2B45x-168=0...factor
-3+%28x%5E2-15x%2B56%29+=0
-3+%28x%5E2-8x-7x%2B56%29+=0
-3+%28%28x%5E2-8x%29-%287x-56%29%29+=0
-3+%28x%28x-8%29%2B7%28x-8%29%29+=0
-3%28x-8%29%28x-7%29=0
solutions:
x=8
or
x=7
the number of $1 discounts that will yield sales of $468 per week is: 7 and 8