SOLUTION: Lisa sold b candy bars for d dollars. Jack bought them for $0.20 less per candy bar. How many candy bars could Jack buy for $20?

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Question 1081209: Lisa sold b candy bars for d dollars. Jack bought them for $0.20 less per candy bar. How many candy bars could Jack buy for $20?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Lisa sold b candy bars for d dollars.
You want to find [ dollars ] / [ candy bar ]
which is +d%2Fb+, the price of 1 candy bar.
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Jack bought +b+ candy bars for:
+d%2Fb+-+.2+ dollars each
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In words:
[ Jack's $20 ] / [ Jack's price per candy bar ] = [ number that he can buy ]
+20+%2F+%28+d%2Fb+-+.2+%29+
I can multiply top and bottom by +b+
+20b+%2F+%28+d+-+.2b+%29+ = number he can buy
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check answer:
Suppose +b+=+4+ and +d+=+4.8+
+d%2Fb+=+1.2+
+d%2Fb+-+.2+=+1+
Jack's price per candy bar is $1
For $20, he can buy:
+20b+%2F+%28+d+-+.2b+%29+
+%28+20%2A4+%29+%2F+%28++4.8+-+.2%2A4+%29+
+80+%2F+%28+4.8+-+.8+%29+
+80+%2F+4+=+20+ bars
OK