another way of looking at it is just find the average amount charged(the middle number in this case) -> 1500, and multiply by the # of times charged (3000), and

another way of looking at it is just find the average amount charged(the middle number in this case) -> 1500, and multiply by the # of times charged (3000), and there ya go, its really the same math at kjay's, but just approaching it a different way.