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.
The answer is 3.4 because 30 can’t be divided equally into 9, reason being that 9 x 30 = 270 which doesn’t make sense, so you have to divide 30 equally into 9 parts then turn it into a ratio.