Answer
$(c+3)(c-18)$
Work Step by Step
$c^2-15c-54$ has no common monomial factors
$=(\ \ \ \ \ \ \ \ )(\ \ \ \ \ \ \ \ )$
$=(c\ \ \ \ \ \ )(c\ \ \ \ \ \ )$
$=(c+\ )(c-\ )$ The factors of -54 must have unlike signs.
$=(c+3)(c-18)$ 3 and -18 have a sum of -15 and a product of -54.
