I do not know how the 1's cancel out to give 1/3^x

Unfortunately your teacher is using x as both a variable and a multiplication sign. This is something that can be avoided by using something like the asterisk symbol to indicate multiplication.

Anyways, notice how the expression shows up twice. Once in the numerator (the entire numerator) and once again in the denominator (nearly the whole thing)

Let's replace that messy expression with the variable y. So we're letting

This means,

At this point you can probably see how to get from here. The y terms cancel out when we divide leaving 1 up top and 3^x down below.

168

step-by-step explanation:

first off, we know that he drove 3.5 hours at a rate of 48 mph.

knowing that, we want to see how many miles he drove all-together.

in this case, we can just multiply 48 by 3.5.

48 * 3.5 = 168

the answer is b.

64

step-by-step explanation:

c=2πr=2·π·8≈64