Adding and Subtracting Complex Numbers

We add the real parts and add the imaginary parts.

1. ⓐ
   $\begin{array}{ccc}\hfill (3-4i)+(2+5i)& =& 3-4i+2+5i\hfill \\ & =& 3+2+(\mathrm{-4}i)+5i\hfill \\ & =& (3+2)+(\mathrm{-4}+5)i\hfill \\ & =& 5+i\hfill \end{array}$
2. ⓑ
   $\begin{array}{ccc}\hfill (\mathrm{-5}+7i)-(\mathrm{-11}+2i)& =& \mathrm{-5}+7i+11-2i\hfill \\ & =& \mathrm{-5}+11+7i-2i\hfill \\ & =& (\mathrm{-5}+11)+(7-2)i\hfill \\ & =& 6+5i\hfill \end{array}$