How many pounds of the premium 20¢ per pound seed did he use in the mixture?

Question

Farmer Wakenbush mixes last year’s sunflower seed, worth 15¢ per pound, with premium seed, worth 20¢ per pound, to produce a mixture of 50 pounds of seed worth 18¢ per pound.

Answer 1

Let s = last year's sunflower seed and p = premium seed

s + p = 50

.15s + .20p = .18*50

Either use the elimination method or rewrite the first equation to use substitution, and solve for one of the variables, then you can plug it back in to solve the other.