The answer is C (a + 3 = b) <<<<<==== answer.
Okay, so one of the geometric theorems is that two of the inside angles equals the outside angle in a situation like this one.
So, set them equal:
2x+ 2 + 4x + 8 = 8x - 30
Combine like terms:
6x + 10 = 8x - 30
40 = 2x
x = 20
The price per cubic inch for the extra large tub will probably be 2000