What is the perimeter of ^pqr with vertices p(-2,9) q(7,-3) and r(-2,-3) in the coordinate plane?

On a piece of paper graph f(x)=5•(0.4)^x

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?

Ineed to know the answer to this algebra question.