Given:
f(x)=4x-3
f(x) +g(x) =9x +4
To find:g(x)
Solution:
f(x) + g(x) =9x +4
Replacing f(x) with its value.
4x -3 +g(x) = 9x +4
=> g(x) = 9x+ 4 -(4x-3)
=> g(x) = 9x+4 -4x +3
=> g(x) = 5x +7
Hence;
Option A g(x)=5x+7 is the answer.
Hope it helps...
Regards;
Leukonov/Olegion.