When we are given a function f(x) and we are asked for f(a) [a is any number], it means to replace (or substitute) a into x in the function (x=a)
In this problem, we are asked to replace x with 2 in f(x), the first equation, and replace x with 3 in the second equation.
It looks like this:
f(2) = 2^3 + 5(2)^2 = 8 + 5(4) = 8 + 20 = 28
g(3) = 2(3) + 4 = 6 + 4 = 10
We finally just add these two numbers from f(2) and g(3) and get 28 + 10 = 38