Given function is

Or,

First step is to find the inverse is switch a and b. Therefore, the above equation will be:

b = 5*(a + 7) By simplifying.
b = 5a + 35
Next step is to solve the equation for a to get the inverse of a (b). So, subtract 35 from each sides to isolate a. Hence,
b - 35 = 5a



Therefore , the inverse is
.
So, c is the correct choice.