Eight roses and 9 Carnations cost $50. One dozen roses and find carnations cost $70. What is the cost of one rose and one Carnation each?
8 r + 9 c = 50
12 r + some strange number c = 70
24 r + 27 c = 150
24 r + 2*strange* c = 140
------------------------subtract
0 r + (27-2*strange) c = 10