The following graph represents the cost and revenue functions for custom-made computers. How many computers have been sold at the break-even point? A graph has sales on the x-axis and cost times 100 on the y-axis. The cost line goes through (0, 5) and (12, 9). The revenue line goes through (0, 0) and (12, 9). The lines intersect at (12, 9). a. 12 b. 9 c. 5 d. 0