the average of 1 st 3 of 4 numbers is 6 and of the last 3 are 5 . if the sum of the first and the last number is 17 . what is the last numbers ?
"a + b + c = 18 b + c + d = 15 a + d = 17 a – d = 3 a + d = 17 2 d = 14 d = 7 answer : d"
subtract(subtract(multiply(3, 6), add(subtract(17, 6), 3)), 6)