what is the average ( arithmetic mean ) of the numbers 5 , 6 , 7 , 7 , 8 , and 9 ?
"{ 5 , 6 , 7 , 7 , 8 , 9 } = { 7 - 2,7 - 1 , 7 , 7,7 + 1,7 + 2 } - - > the average = 7 . answer : d ."
divide(divide(multiply(add(5, 7), add(divide(subtract(7, 6), 5), const_1)), const_2), add(divide(subtract(7, 5), 5), const_1))