How many gallons of a 60% alcohol solution must be mixed with 90 gallons of 25% alcohol to get a mixture that is 50% alcohol?
Let the number of gallons of the 60% alcohol solution =G
0.60G + 0.25 * 90 = 0.50 * [G + 90], solve for G
G = 225 gallons of 60% alcohol solution will be needed.
