SOLUTION: A contractor mixes concrete from bags of pre-mix for small jobs. How many bags with 11% cement should he mix with 10 bags of 12.5% cement to produce a mix containing 12% cement?

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Question 1162615: A contractor mixes concrete from bags of pre-mix for small jobs. How many bags with 11% cement should he mix with 10 bags of 12.5% cement to produce a mix containing 12% cement?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
b number of bags of the 11%
10 bags of the 12.5%
Total Number Bags, b+10

11b%2B12.5%2A10=12%28b%2B10%29
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11b%2B12.5%2A10=12b%2B120
11b%2B125=12b%2B120
highlight%285=b%29