Step-by-step explanation: To find the cost of one pickle, we can use a system of equations. Let x be the cost of one pickle and y be the cost of one popcorn box. Then we have:
2x + 2y = 10 4x + 2y = 13.50
Subtracting the first equation from the second, we get:
2x = 3.50 x = 1.75
So one pickle costs $1.75.