There are 6 balloons, and they all descend at the same speed (240 ft) and the same rate (1 minute). They descend for 5 minutes straight. So, all we need to do is multiply the speed (240) and the time (5 minutes), which is 1,200 feet per balloon. Lastly, just multiply 1,200 by 6 to get the total change in altitude, and that would be 7,200 feet.