In a complex circuit, three colored wires (red, green, and blue) are joined together inside a mysterious black box. An ammeter, a device that measures the rate of charge flow (current), shows you that charge enters the box at 3 coulombs per second through the red wire and leaves the box at 2 coulombs per second through the green wire. There is no buildup of charge inside the box. After 10 seconds has elapsed, how much charge has flowed out of the box through the blue wire?