find the average of first 4 multiples of 9 ?
"average = ( 9 + 18 + 27 + 36 ) / 4 = 22.5 answer is c"
divide(add(add(add(4, const_1), add(add(4, const_1), const_2)), add(subtract(9, 4), subtract(9, const_2))), 4)