Hurr plzenter the values for the highlighted variables that show how to subtract the rational expressions correctly: abcdefg

For a we have:
 x ^ 2 + 6x = x (x + a) = x (x + 6)
 a = 6

 For b we have:
 b = 2

 For c we have:
 x-c = x-6
 c = 6

 For d and e we have:
 bx-x + c = dx-x + e
 b = d = 2
 c = e = 6

 For f we have:
 dx-x + e = x (d-1) + e = x (2-1) + e = x + e = x + f
 e = f = 6

 For g we have:
 (x + f) / (x + 6) = (x + 6) / (x + 6) = g = 1
 g = 1

The answer would be a