Answer:
see the attachment
Step-by-step explanation:
The break-even point is on both curves. The y-intercept can be used for the other point in each case.
The break-even point is where cost and revenue are the same:
  20/3x +50 = 10x
  50 = 10/3x . . . . . . . . subtract 20/3x
  15 = x . . . . . multiply by 3/10
  r = c = 10(15) = 150 . . . . for x = 10
Two points you can use for graphing the lines are ...
  cost: (0, 50) and (15, 150)
  revenue: (0, 0) and (15, 150)