A gardener is mixing two fertilizers. The first contains 44% of quality soil and the second contains 71% quality soil. To get 18 pounds of the mixed fertilizer with 63.5% of the quality soil, how many pounds of the first brand of soil will she need?
Let X = the number of pounds of soil 1
18-X = the number of pounds of soil 2
.635*18 = 11.43 lbs of quality soil
11.43 = .44X + .71(18-X)
= .44X + 12.78 - .71X
Rearranging: .27X = 1.35
X = 5 lbs of soil 1