Having a $75 added cost to the total price, we can presume they will never equal. It is easy to see if you make it algebraic:

They will never equal each other.
Πr²h=175
πr²*7=175
Divide both sides by 7
πr²=25
Divide both sides by π (3.14)
r²=7.96
Square root of 7.96=2.82
r=2.82
Diameter is 2r. 2.82*2
2.82*2=5.64
Answer:
d=1
Step-by-step explanation:
Factor d^2 - 2d - 8 into (d-4)(d+2)
Move -2/d+2 onto the other side, changing it into 2/d+2.

Let the empty side equal zero.
Add 3/d-4 and 2/d+2

Then add that to -3d.

Multiply 0 by d+2 and d-4 to get 2d-2 by itself.
2d=2
d=1
I can't edit the equation, but it's d-4 althroughout the question. Sorry for being so slow.