Answer:
0.0526 gallons
Step-by-step explanation:
Here is another way to set up the solution. (It will give the same answer as Michael's solution.) w = number of gallons of pure waterYou have 1 gallon of pure antifreezeYou want 95% antifreeze in 1+w gallons You can do a weighted combination of concentrations of antifreeze. (0%)(w) + (100%)(1) = (95%)(1 + w) 100 = 95(1 + w) w = 100/95 - 1 ≅ 0.0526 gallons