Okay this is the basic when there is a - + + = -
You have to multiply the length by the width and the sum of that you will multiply by the height. In this case 13.5 times 12 is 162. So 162 times 14.1 is 2284.2
√5 = 5^(1/2)
Multiplying two number with the same base has as result a number with the same base and the sum of the exponents so:
1/2 + 3 = 7/2
which means
5^3 x 5^(1/2) = 5^(7/2)
9 ten-thousands is 9*10,000=90,000. 90,000/10 is 9,000, or nine thousands.