3. Aisha is making greeting cards, which she will sell by the box at an arts fair. She paid $20 for a booth at the fair, and the materials for each box of cards cost $6. She will sell the cards
for $10 per box of cards. At some point, she will sell enough cards so that her sales cover her
expenditures. How much will the sales and expenditures be? How many cards will that take?