SOLUTION: PLEASE HELP WITH THE ANSWER TO THIS QUESTION: Books cost 40 cents and pamphlets 5 cents at the book sale. If Donnie spends $4.15 at the book sale and purchased 20 more pamphlets t

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Question 207172This question is from textbook Algebra I: Incremental Development
: PLEASE HELP WITH THE ANSWER TO THIS QUESTION:
Books cost 40 cents and pamphlets 5 cents at the book sale. If Donnie spends $4.15 at the book sale and purchased 20 more pamphlets than he did books, how many pamphlets did he buy?
Thank you!
This question is from textbook Algebra I: Incremental Development

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
let B = number of books purchased.
let P = number of pamphlets purchased.
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.40 * B + .05 * P = $4.15
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Donnie purchased 20 more pamphlets than he did books.
this means that P = B + 20 which means that:
the number of pamphlets is equal to the number of books plus 20.
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Since P+=+B+%2B+20, we can substitute B+%2B+20 for P in the money equation to get:
.40+%2A+B+%2B+.05+%2A+%28B+%2B+20%29+=+4.15
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simplifying this equation, we get:
.40+%2A+B+%2B+.05+%2A+B+%2B+.05+%2A+20+=+4.15 which becomes:
%28.40+%2B+.05%29+%2A+B+%2B+%28.05+%2A+20%29+=+4.15 which becomes:
.45+%2A+B+%2B+1.00+=+4.15 which becomes:
.45+%2A+B+=+3.15 which becomes:
B+=+3.15+%2F+.45+=+7
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7 books are purchased and 27 pamphlets are purchased.
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total cost is %287+%2A+.40%29+%2B+%2827+%2A+.05%29+=+2.80+%2B+1.35+=+4.15
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