Question 66506
(5m - 6n + 7)(2m - 3n - 4)

to multiply out this term we use a method known as foiling. You multiply each term in the first equation by each term in the second equation.
I will break this down step by step.
Take 5m and multiply it.
5m(2m - 3n - 4)
10m^2-15mn-20m (hold onto this we will use it later.)
now -6n

-6n(2m - 3n - 4)
-12mn+18n^2+24n(hold onto this we will use it later.)
now we will multiply out 7.
7(2m - 3n - 4)
14m-21n-28

You now take all the results from the foil process and line them up.

10m^2-15mn-20m-12mn+18n^2+24n+14m-21n-28

you combine all like terms
10m^2+18n^2-27mn-6m+3n-28

this is your answer
{{{10m^2+18n^2-27mn-6m+3n-28}}}