8. c+8/12 = c+20/84
84(c+8) = 12(c+20)
84c +672 = 12c+240
84c-12c = 240-672
72c = - 432
c = 6
9. x/15 - 3= x-207/60
4x-180 = x-207
4x-x = - 207+180
3x = - 27
x = - 9
