Answer:
"mix 1 cup of vinegar with 1 gallon of water"
1 cup = 8oz; 1/4 cup = 2oz
You can see that the amount of vinegar is 1/4 of the original amount,
so, we will need 1/4 of the amount of water, which is 1gallon = 128oz
so, 1/4 times 128oz = 32oz, which is one quart
Algebraically, 8oz : 128oz = 2oz : x
8x = 256; x = 32oz