Adairy needs 306 gallon of milk containing 6% butterfat. how much gallons each of milk containing 7% butterfat and milk containing 4% butterfat must be used to obtain the desired 306 gallons?

306 gallons of milk containing 6% butterfat contain 18.36 gallons of butterfat.

x - the number of gallons of 7% milk
y - the number of gallons of 4% milk



204 gallons of 7% milk and 102 gallons of 4% milk should be used.

Y=3x+1 so the first one