What have you attempted thus far? Also, write \le or \leq to generate $\leq$ and \leqslant to generate $\leqslant$. The words in bold are known as commands and are written with a \ in the beginning. To put them into action, add dollar signs at the start and end of each command, i.e. $$\ldots$$
– Mr PieFeb 16 '18 at 09:02