The function f(x) is f(x)=2x+1
The value of f[g(5)] can be obtained if any unknown x in the equation f(x) we replace with g(5). But what is g(5)? We can obtain the value for g(5) if we replace the variable x in g(x) with 5. g(5)=2*5-5=10-5=5
So, f[g(5)] = f(5), f(5)=2*5+1=10+1=11.
