At a concession stand, a pickle and two bags of chips costs a total of $3.25. Three pickles and four bags of chips costs a total of $7.25. To determine the cost of one pickle, Kevin is writing a system of equations. His first equation is shown: x + 2y = 3.25 Which of the following could be the second equation in his system of equations?
3x + 4y = 7.25

4x + 3y = 7.25

3x - 4y = 7.25

(3 + 4)x = 7.25​