Barney's bicycle shop is selling t-shirts at the local health fair. they plan on selling shirts for $8 each. to have the shirts made, barney's bicycle shop pays the shirt maker $3.50 per shirt plus an initial fee of $63. how many shirts must barney's bicycle shop sell before they can make a profit?

a. 9 shirts
b. 8 shirts
c. 14 shirts
d. 11 shirts

So they plan to sell each shirt at 8 bucks, thus, hmmm let's say they sell "x" shirts, then the Revenue is 8*x, or 8x, the income from the sales.

now, to make each, they need to pay the shirt maker 63 bucks first and 3.50 for each shirt she makes, so, if they sell "x" shirts, the Cost is 63 + 3.50x.

now, Profit, is just the surplus made from the sales after you remove all your expenses for making the sales, namely, Revenue - Costs.

the point right before Profit, the point at which Revenue is the same as Costs, namely, you're not making any profit, but you're not losing any money either, is the break-even point.  And that happens, yes, you guessed it, when Revenue = Costs.

8x = 63 + 3.5x

and fairly sure you know how much that is.