Prove that if $g(x)$ is continuous at $a$ and $f(x)$ is continuous at $f(g(a))$ then the function composition $(f\circ g)(x)$ is continuous at $a$.

Problem: 

Prove that if $g(x)$ is continuous at $a$ and $f(x)$ is continuous at $f(g(a))$ then the function composition $(f\circ g)(x)$ is continuous at $a$.

Answer: 

It is true that if $g(x)$ is continuous at $a$ and $f(x)$ is continuous at $f(g(a))$ then $(f\circ g)(x)$ is continuous at $a$.