Question 29925
Probably the problem is f(x) = (7x+3)/8
Let  f(x) = y
Then y =(7x+3)/8
Which gives  8y = 7x+3
8y-3 = 7x
x = (8y-3)/7
Putting x in the place of y, the above x becomes inverse of x
Therefore inverse of x 
=  (8x-3)/7
Which is your choice (d) provided you put the bracket for the whole (8x-3)
Note: For every funciton it is custormary to call the domain arbitrary member to be x and hence for the new function: f inverse of x  which is also a function in x and hence replace y by x for the inverse function consideration!