Based on the equation we see that the thumb drives cost $200 which is why that is being subtracted. To calculate the break-even number of sales we need to make a total of 200 to cover the costs. We calculate this by matching the equation to 0 and solving for x...
0 = 8x - 200 ... add 200 on both sides
200 = 8x ... divide both sides by 8
25 = x
Finally, we can see that the committee will break even after selling 25 thumb drives which would make them $200 to cover all of their costs.
This is a question of randomness so there really is no answer. I would guess 7 since that is the center page and you're more likely to open it up in or near the middle
