Soybean meal is 14% protein; cornmeal is 7% protein. How many pounds of each should be mixed together in order to get 280 lb mixture that is 12% protein

Work:.14x+.07 (280-x) =.12*280

.14x+19.6-.07x=33.6

.07x=33.6-19.6

.07x=14

x=14/.07

x=200 lbs of soybeans is used.

280-200=80 lbs. of cornmeal is used.

.14*200+.07*80=.12*280

28+5.6=33.6

33.6=33.6