Ashley spent $228 on 6 rose bushes and 18 shrubs. Heather spent $139 on 8 rose bushes and 9 shrubs. What is the cost of one rose bush and one shrub.
+23245 R = cost of one rose bush
S = cost of one shrub
6·R + 18·S = 228 ---> 6·R + 18·S = 228
8·R + 9·S = 139 ---> multiply by -2 ---> -16·R - 18·S = -278
Adding down the columns: -10·R = -50
R = 5
Since 8·R + 9·S = 139 ---> 8·5 + 9·S = 139 ---> 40 + 9·S = 139 ---> 9·S = 99 ---> S = 11
