The FOIL method is the formula that is used when multiplying 2 binomials, where
(a+b)(c+d) = a(c+d) + b(c+d) = ac + ad + bc + bd
Using the formula above, apply the foil method.
4(-5+4i) - 3i(-5+4i)
4(-5) + 4(4i) + (-3i(-5)) + (-3i(4i))
-20 + 16i + (15i) + (-12i^2)
-20 + 16i + 15i - 12i^2
Since i^2 = -1, then
-20 + 16i + 15i - 12(-1)
-20 + 16i + 15i + 12
Hope this helps.
