Try taking it one step at a time and multiplying each set one by one. watch the negative signs! remember: a negative times a positive is negative, and a negative times a negative is positive! -2m(m+n-4)= -2m^2 -2mn+8m next: 5(-2m+2n) = -10m+10n next: n(m+4n-5) = nm + 4n^2-5n
you're left with -2m^2-2mn+8m-10m+10n+nm+4n^2-5n now, add "like terms" (aka terms that have the same letters and powers, like 10n and -5n) So, -2m^2-nm-2m+5n+4n^2 is your answer! (answer choice C.)
