Question 159103
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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Let x = bags of 11% cement to be added
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"cement from 11%" + "cement from 12.5%" = "total cement in mix"
.11x + .125(10) = .12(10+x)
.11x + 1.25 = 1.2 + .12x
1.25 = 1.2 + .01x
.05 = .01x
5 bags = x