There is a specialty store that you like to go to when you are craving jelly beans. The price is reasonable at $1.30 per pound. The store is a bit of a distance away and you could purchase the same jelly beans at your neighborhood supermarket, but the cost is a little more at $2.10 per pound. You spend about $3 on gas every time you go to the specialty store. How do you know if you are getting enough of the jelly beans to make the trip worthwhile?