By using the F.O.I.L method: , the question is binomial so the answer will be trinomial;
First = m²
Outer = -3
Inner = 4m
Last = -12
so the answer should be : m² - 1m - 12 . not m² + m - 12 . .
because when you solve the Outer -3 & Inner +4 , it has different sign so the sign will be -(negative) so that's why the result is -1m not m only . .