A 25 oz solution is 20 % alcohol.

if 50 oz of water are added to it what % of new solution is alcohol

Alcohol content = 25*0.2 = 5 oz
New total volume = 75 oz
% Alcohol = 5*100/75 = 6.67%

Out of the 25 ounces, alcohol = 25*0.2 = 5 oz

Then you have 5oz alcohol and 20 water

If you add 50 oz of water, you will have alcohol = 5 oz and water = 70 oz and your total of alcohol plus water will be 75oz

so your new percent is 5/75 * 100 = 6.666 %