Let's supposes the number of cups sold is <em>c</em>.
We can use an equation to solve this problem. Since both people are down some money, we will write the number they spent on supplies as negative, and use their rates as the unit rates for each side of the equation.
One way to solve this problem is to set up two expressions: one for your cost and one for your sales. You will break even when both expressions are equal. You can then solve by using inverse operations.
