Soybean meal is 16% protein and corn meal is 9% protein. How many pounds of each should be mixed to get a 350-lb mixture that is 12% protein?

Answer 1

350 lb x 0.12 = 42 lb (total) of protein content.
let S be the mass of soybean meal and C be the mass of corn meal.
S + C = 350
0.16 S + 0.09 C = 42

Solve those two simultaneous equations

0.16 S + 0.16 C = 56

0.07 C = 14
C = 14/0.07 = ?
S = 350 - C = ?