(11 - 9i) - (15 - 12i) Ok so first multiple the subtraction sign into the parenthesis on the right had side of it.
And you get -15 + 12i
So now you have 11 - 9i -15 + 12i Combine Like terms
-9i + 12i = 3i
11 - 15 = -4
So your answer is 3i - 4
Hope you find this to your liking
