Let $f,g : \mathbb{R}^{n}\to [0,+ \infty] $ 2 Borel measurable functions. Show that {${x \in \mathbb{R}^{n}| f(x)<g(x) } $} is a Borel set.
I don't know how to start with the problem. At the beginning I thought I maybe could divide it into small intervals, but the function must not be continuous, so I don't know...
Thanks for help