You add 7 more to 46 and the answer would be 53.
Using the given equation and edge length:
V = 45^3
V = 45 x 45 x 45
V = 91,125 cubic meters
Yes. Since 12 3/4 cups can be rounded up to 13 and 6 5/6 can be rounded up to seven, and 13+7 equals 20, so you would be able to put the additional amount if cups into the cooler.
