A dairy needs 244 gallons of milk containing 7% butterfat. How many gallons each of milk containing 9% butterfat and milk containing 1% butterfat must be used to obtain the desired 244 gallons?
Let x gallons be the amount of milk containing 9% butterfat and y gallons be that of milk containing 1% butterfat.
We have {x+y=244(9%)x+(1%)y=(7%)(244) by considering the total amount of milk and the total amount of butterfat respectively.
Can you continue solving for x and y from here?