How many gallons of a 90% antifreeze solution must be mixed with 100 gallons of 20% antifreeze to get a mixture that is 80% antifreeze? Use the six-step method. Strength Gallons of Solutions Gallons of Antifreeze 90% x 20% 100 80% xplus100 Question content area bottom Part 1 You need enter your response here gallons. (Round to the nearest whole number.)