Write the sum or difference in the standard form a + bi.

( 4 – 2i) + ( 9 + 6i)

(4-2i) + ( 9 + 6i) =
4-2i + 9 + 6i=
13 + 4i

The importance here is to sum real number with real numbers and imaginary number with imaginary numbers. Do not mix them. Imaginary number is the number that has "i" next to it.