On Earth Day, in Wilder Bowl, Emily had 30 tie-dyed t-shirts to sell at the rate of 3 for $20.00. Liz had 30 slightly fancier t-shirts to sell at the rate of 2 for $20.00. Emily suddenly got sick and asked Liz to sell her shirts for her. Liz agreed. Finding the difference in price a bit hard to keep track of, Liz decided to combine everything and sell all the shirts at 5 for $40.00, a reasonable decision. After everything sold out, which it did, Liz dropped off Emily’s $200. But then, to her surprise, instead of the $300 she expected to have left for herself, she had only $280. What happened to the other $20.00?
| Emily (30 shirts) | Liz (30 shirts) | both (60 shirts) | |
| at original price | $6.67 (20/3) | $10 | |
| brings in | $200 | $300 | $500 |
| at new price (40/5) | $8 | $8 | |
| $240 | $240 | $480 |
Under Liz’s system, Emily’s shirts brought in $40 more, but Liz’s brought in $60 less.