Question

Milk that is 4% butterfat is mixed with milk that is 1% butterfat to obtain 18 gallons of milk that is 2% butterfat. how many gallons of each type of milk are needed?

Answer 1

0.04x+0.01y=0.02(18)
x+y=18

solve the system
0.04(18-y)+0.01y=0.36
-0.03y=-0.36
y=12
x=18-y
x=6
6 gallons for 4%
12 gallons for 1%