So we first need to find a number of cups leaking in a week. Which is simple just multiply 1.5 by 7
1.5 x 7 = 10.5.
Now we convert by knowing how many cups are in a gallon. Since there are 16 cups in a gallon we divide 16 by our total.
16/10.5 = about 1.5
So the amount of gallons leaked per week is 1.5