Question 135413
Find g(a+1) when g(x)= 1/4x - 3.

Do you see x in the function g(x)?

Replace every x with (a + 1) and simplify.

g(a + 1) = 1/4(a + 1) - 3

g(a + 1) = 1/4a + 4 - 3

g(a + 1) = 1/4a + 1

Did you follow?  I just found the value of g(a + 1) and it is the fraction
1/4a + 1