The addition of the function is:
(f+g)(x)= f(x)+g(x)
So, (f+g)(5)= f(5)+g(5)
To find f(5) and g(5), plug in 5 for x in both the functions.
So, f(5)= 8(5)-13 = 40-13 = 27
g(5)= 5-9= -4
Now we can add f(5) and g(5) to get the answer.
So, (f+g)(5)= 27 +(-4) = 27-4= 23
Hence, (f+g)(5)= 23
