Question

Find how many quarts of 4% butterfat milk and 1% butterfat milk should be mixed to yield 90 quarts of 2 % butterfat milk.

Answer 1

let the amount of 4% milk be x
then the amount of 1% mild is 90-x

.04x + .01(90-x) = .02(90)
multiply by 100
4x + 1(90-x) = 2(90)
4x + 90 - x = 180
3x = 90
x = 30

add 30 quarts of 4% with 60 quarts of 1%