Let's call the sum of the 10 numbers A, and the sum of the 4 numbers with an average of 60 B. We know that A/10 = 72, so A = 720, and that B/4 = 60, so B = 240. We want to find the average of the other 6 numbers, which means we want to find the sum of those 6 numbers divided by 6. The sum of the other 6 numbers is A - B = 720 - 240 = 480. Then, the average of the other 6 numbers is 480 / 6 = 80. So, the average of the other 6 numbers is 80.
