Question

A student government organization is selling Christmas trees as a fundraiser. On Friday, they sold 5 noble fir trees and 3 douglas fir trees for a total of $420. On Saturday, 12 noble fir trees and 9 douglas fir trees were sold for a total of $1,080. What is the cost per tree for each type?

Answer 1

9d+12n=1080
3d+5n=420

multiply the second equation by-3
9d+12n=1080
-9d-15n=-1260 subtract

-3n=-180
N=60 noble fir trees

9d+12 (60)=1080
Solve for d
D=40 douglas fir trees