(2+5i)+(-3-4i) what is the answer to this question?

Just tell me how to set up the equation.

Galen sold tickets of his church’s carnival for a total of $2,820. children’s tickets cost $3 each and adult tickets cost $5 each. the number of children’s tickets sold was 30 more than 3 times the number of adult tickets slod. how many children’s ticket and how many adult tickets did he sell?

The measure of one angle of an octagon is two times smaller that of the other seven angles. what is the measure of each angle?