answer: c. 13 + 3i
(6 + 3i) + (8 + 4i) - (1 + 4i)
(6 + 3i) + (8 + 4i)
(since you're adding, there's no need to change signs, just add like terms)
6 + 8 = 14 3i + 4i = 7i
7i + 14
(7i + 14) - (1 + 4i)
(since you're subtracting, you have to change signs for the second binomial and then add like terms)
7i + 14 - 1 - 4i
7i - 4i = 3i 14 - 1 = 13
3i + 13