You’re given g(x) = x^2 - 5
When asked to find g(9), you’re being told that x=9, since the x in the g(x) was replaced by 9.
So that’s telling you to put 9 in for all x’s:
g(9) = (9)^2 - 5
You then just need to clear up the right hand side.
9^2 - 5 = 81 - 5
= 76
So, g(9) = 76
