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? What two equations would you use to determine your break-even point?
(Let C stand for the total cost and x represent the amount of jelly beans.)
The answer would be A, assuming you don't need gas to go to the neighborhood store.
since every time you go to the faraway store, you spend the same amout no matter what, you know its just 3. not 3x. and since the cost depends on how many pounds of jelly beans you get, that would be 1.30x. so in total, the first equation would be C=1.3x+3
now the next one has just the cost of jelly beans per pound, 2.10 per pound. so thats 2.1x, so C=2.1x