Word problem

Soybean meal is 16% protein; cornmeal is 8%. How many pounds of each should be mixed together in order to get 320-Ib mixture that is 11% protein?

Let x be a portion of the 16% protein, then,

320 - x, is the portion of the 8% protein but,

.16x + .08(320 - x)=320*11%

.16x +25.6 - .08x=35.20 re-arrange

.08x=9.60 divide both sides by .08

x=120 Pounds of the 16% protein, and

320 - 120=200 Pounds of the 8% protein