I went to my favorite taco stand with some friends. Between us we bought 6 tacos and 2 burritos, and I noticed that the ratio of the amount we spent on tacos to the amount we spent on burritos was 7:4. Later we went back and bought 4 tacos and 3 burritos and spent 1 dollar less. How much money did we spend that time?
This problem leads to a negative price for tacos. If you ever find this please let me know.