-4 x 52 = -208
208. There are four 5-cards in each deck. 4x52=208.
At 7.48 gallons per cubic foot that is 3.14x30x30/4x52 x7.48 /12 = 22,900 gallons
The answer is 13. This is calculated by adding the frequencies together: once a year (1) + two times a month (2x12=24) + four times a week (4x52=208) + 16 times a year (16). 1 + 24 + 208 + 16 = 249, which simplifies to 13 times a year.