Suppose that the sequence of random variables $\{X_{n}\}$ converges to a random variable $X$ in distribution, and a numeric sequence $a_n$ converges to $1$. Prove that $a_nX_n$ converges to $X$ in distribution.
I'm not quite sure how to approach this problem. I recently learned about Weak Convergence, but that seems to be no help here. For example, I am aware of Prokhorov's Theorem, but that seems to be useless here. So I am instead trying to use different inequalities, like Markov's, Chebyshev, etc. I'm studying for my exam and will greatly appreciate your help in solving the problem.
Thank you