221
As to the second part of your question, of course, if you memorized the answer you could answer it quickly, or if you solve 30x12 and then add 12 to that answer. doing it like that may be helpful.
16,696.51 gallons. Multiply width times length times depth- that gives the number of cubic feet of volume (2,232 cubic feet) Multiply THAT by the number of gallons in one cubic foot (7.48 gallons)