Soybean meal is 14%protien , cormeal is 7% protien . How many pounds of each should be mixed together to get a 280 pound mixture that is 11 % protien? How much cornmeal? How much protien?

let the amount of soybeans be x pounds,

then the amount of cornmeal would be 280-x pounds

so (14/100)x + (7/100)(280-x) = (11/100)(280)

multiply by 100
14x + 7(280-x) = 11(280)

find x, that is the soybean,
etc.