SOMEONE HELP ME FIND THE MISSING SIDE- (I think it’s 21)

Name these type of angles shown check all that applies

In 2009, there were 1570 bears in a wildlife refuge. in 2010, the population had increased to approximately 1884 bears. if this trend continues and the bear population is increasing exponentially, how many bears will there be in 2018?

Perform the indicated operation and write the answer in the form a + bi. (-5 + 2) + (3 - 6i)