help with the math I'm stuck

Question

soybean meal is 12% protein; cornmeal is 6% protein. how many pounds mixed together in order to make 240lb mixture that is 8% protein?

Answer 1

Let x = # lbs of soybean meal

240-x = # lbs of corn meal

Then, use a weighted average { 12x + 6(240-x) }/240 = 8

Solving for x, we find that x = 80 lbs soybean meal

240-x = 160 lbs corn meal