There are 4 quarts in 1 gallon of milk.
We have 1 3/4 gallons.
1/4 gallon = 1 quart, so we can already tell we have 3 quarts by the "3/4".
We also have 1 whole gallon which is 4 quarts, so we add 4 quarts to 3 quarts to get 7 total quarts.
Your answer is 7 quarts.