(6 bottles) x (16 ounce/bottle) = 96 ounces
(1 pitcher) x (1/2 gallon/pitcher) x (128 ounce/gallon) = 64 ounces
Total ounces taken from the full tank= (96 + 64) = 160 ounces
Ounces left in the water tank =
(Ounces in the tank before Tom started taking them out) minus (160) .