Let's deal with each factor in the numerator individually first: when evaluating the power of a power, you have to multiply the exponents: 
So, we have
^{-\frac{1}{2}} = 3^{2\cdot(-\frac{1}{2})} = 3^{-1},\quad (9^4)^{-1} = 9^{-4}](https://tex.z-dn.net/?f=%20%5Btex%5D%283%5E2%29%5E%7B-%5Cfrac%7B1%7D%7B2%7D%7D%20%3D%203%5E%7B2%5Ccdot%28-%5Cfrac%7B1%7D%7B2%7D%29%7D%20%3D%203%5E%7B-1%7D%2C%5Cquad%20%289%5E4%29%5E%7B-1%7D%20%3D%209%5E%7B-4%7D)
Now remember that
and
to rewrite the expression as

Now use the rules

to conclude

There is no given information saying how much money Tom has, so you can eliminate A and B, and he is the one in debt to both his aunt and uncle, so you need to add $11 and $12 to get $23, which is C
For the first 8 hours he makes $12.00 per hour.
$12.00 * 8 = $96.00
Now you have $128.00 = 16.00h + $96.00
Subtract 96 from each side:
32 = 16h
Divide both sides by 16:
h = 2
He worked 2 hours of overtime.
The common denominator for each of these terms is x^3 so the new expression would be:

so to simplify that down to a single fraction