The correct answer is H. Think of the answer as the two tanks themselves, with the left side being the tank leaking water and the right side of the equation being the empty tank water is coming into. The leaking tank started with 340 liters, and is leaking at a rate of 6 liters every minute (6x). So the left side of the equation (our leaking tank) can be modeled by 340-6x. The right side of the equation (the tank being filled) had no water to start, and is taking all the water that leaks out of the original tank, so 6x. Hence, 340-6x=6x
