No, you need to divide by $\displaystyle 12^3$...essentially a 12 for each of the 3 spatial dimensions.

$\displaystyle 7128\text{ in}^3\cdot\left(\frac{1\text{ ft}}{12\text{ in}} \right)^3=\frac{7128}{12^3}\,\text{ft}^3=156.75 \text{ ft}^3$

Oh, ok that makes since. So for part 5 would I use the formula 1/2*b*h so 1/2*(99)*(104) = 5148 in^2

No, you have a trapezoid, not a triangle. You want to use:

$\displaystyle A=\frac{h}{2}(B+b)$

where:

$\displaystyle h=99$

$\displaystyle B=104$

$\displaystyle b=32$

O.k., sorry for not getting this right away, thanks for your patience lol.
So the answer would then be 6732

An impatient person has no business trying to help on a forum. You are doing fine.

Yes, that is the correct answer. Now, in order to find this area using integration, I recommend orienting your coordinate axes such that the origin is at the bottom corner under the lowest point of the ceiling. We will then want to write the upper slanting edge of the wall as a linear function. What would the y-intercept and the slope be?

Would the slope be 8 and the y-intercept 32?

You have the correct intercept, but for the slope, think of the rise over run of an individual step.

ok so the slope would be 8/11?

Yes, good work! So, what would the linear function representing the slanted edge be?

(8/11)x+32?

Exactly! Now, over what interval do you want to integrate?

Would it be from 5 to 13?

and if that is the interval would it be:
(4/11)x^2+32x evaluated from 5 to 13= 308.364