There are, however, some very simple ways to improve your writing and make it sound more formal and academic. Here are some useful synonyms of some common simple words that are often used:
a lot of = a great deal of
different (adj) = various
often (adv) = frequently
because = as, since, for
happen (v) = occur
show (v) = portray, indicate, highlight
roughly (adv) = approximately
but = however
and = in addition
because of = owing to
reason (n) = explanation