SOLUTION: Christina makes 9.25 purchase at a bookstore with $20 bill. The store has no bills and gives her the change in quarters and dollar coins. There are 19 coins in all. How many of eac
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Question 1011132: Christina makes 9.25 purchase at a bookstore with $20 bill. The store has no bills and gives her the change in quarters and dollar coins. There are 19 coins in all. How many of each kind are there? Answer by addingup(3677) (Show Source):
You can put this solution on YOUR website! How much did she get back?: 20-9.25 = 10.75
She got q(quarters) and d(dollar) coins
q+d= 19 coins in all. If we subtract d from both sides:
q= 19-d is how many quarters she got. Let's use this value for q next:
.25q+1d= 10.75 Substitute for q:
.25(19-d)+d= 10.75 (note: 1d is the same as simply d). Multiply on left:
4.75-.25d+d= 10.75 subtract 4.75 both sides and subtract d's on left:
.75d= 6 Divide both sides by .75:
d= 8 So she got 8 dollar coins back, and:
19-8= 11 quarters back.
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Check:
8*1 = 8
11*0.25= 2.75
8+2.75= 10.75 And this is exactly how much she got back. We have the correct answer.
J
