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
both the equations are shown in A