Math
posted by Ryan on .
Find how many quarts of 4% butterfat milk and 1% butterfat milk should be mixed to yield 90 quarts of 2 % butterfat milk.

let the amount of 4% milk be x
then the amount of 1% mild is 90x
.04x + .01(90x) = .02(90)
multiply by 100
4x + 1(90x) = 2(90)
4x + 90  x = 180
3x = 90
x = 30
add 30 quarts of 4% with 60 quarts of 1%