4 (8m - 7n) + 6 (3n - 4m)

You must first multiply the terms in parentheses by the numbers outside them. so 4 x (8m-7n) and then 6 x (3n-4m). you will then be left with (32m-28n) +

(18n - 24m). then take away the parentheses and combine like terms to get the answer of 8m-10m.