You may want to review complex numbers first.

Adding and subtracting complex numbers is pretty easy. You just
collect like terms. For example, suppose you have to subtract 3
− (−1 + *i*). Then the 3 and the −1 are
like terms, so you can subtract them to give 4. The *i*
doesn't combine with the others, since it has as *i* in it.
So the answer is 4 − *i*.

If there was more than one imaginary term, then we would combine them, just like we combined the two real terms here.