Answer:
9) y = -x + 5
10) y = -7/2x - 5
11) y = x - 1
12) y = -5x/3 - 3
13) y = -4x/1
I'm not 100% sure for some of these answers since the pic is a bit blurry, but they're pretty accurate.
It costs $189-(4×$20) which is $189-$80=$109
410.3ft^3. is correct
volume of the sphere with 3ft radius :

volume of the sphere with 5ft radius:

difference

good luck
The answer is 25 because 4 x 25 is 100