Find how many quarts of 5 % butterfat milk and 2 % butterfat milk should be mixed to yield 30 quarts of 3 % butterfat milk

10 quarts of 5% with 20 quarts of 2% buttermilk

Step-by-step explanation:

x + y = 30 where x = volume of 5% and y = volume of 3%

0.05x + 0.02x = 0.03 (x + y)

0.02x - 0.01y = 0 Multiply through by 100

2x - y = 0

Add the above equation to the first equation:-

3x = 30

x = 10

so y = 30-10 = 20