Amount of water leaked by the pipe per day = 1.5 cups
Number of days in a week = 7
Then
Amount of water leaked by the pipe in 7 days = (1.5 x 7) cups
= 10.5 cups
It is already given in the question that
16 cups = 1 gallon
So
10.5 cups = 10.5/16 gallons
= 0.65625 gallons
= 0.66 gallons
So the pipe is leaking about 0.66 gallons per week. I hope the answer comes to your help.