Why does average variable cost = marginal cost for this function? I was hoping someone could explain the following. Suppose the short-run total cost function is TC = 50 + 12Q. Which of the following statements is true at all levels of production?

The correct answer given was that MC = AVC

Could someone explain to me why please?
So using your above statements in the comments it should be relatively clear how to find that $MC = AVC$. 
$$MC = \frac{\partial TC}{\partial Q} = 12$$
and then using the fact that variable cost is $12Q$
$$AVC = \frac{VC}{Q} = 12$$