Sorry if this is in the wrong place, couldn't think of where to put this; the module's called The Foundations of Calculus, but yeah...

Suppose that $\displaystyle \epsilon>0$. Prove that if $\displaystyle x,l,y\in\mathbb{R}$ and $\displaystyle |x-l|,|y-l|<\frac{\epsilon}{2}$ then $\displaystyle |x-y|<\epsilon$.

I've tried a few stuff with the triangle inequalities and what not and they've lead no where

Cheers in advance.