9C + 2A = $50
10C+ 3A = $61
3(9C + 2A = $50)
-2(10C+ 3A = $61)
27C + 6A = 150
-20C + -6A = -122
-------------------------
7C = 28
7C/7 = 28/7
C = 4
9(4) +2A = $50
36 + 2A =$50
36-36 + 2A= $50-36
2A = 14
2A/2 = 14/2
A = 7
CHECK
9(4) + 2(7) = $50
36 + 14 = $50
$50 = $50
10(4)+ 3(7) = $61
40 + 21 =$61
$61 = $61