the average age of a group of n people is 15 years old . one more person aged 37 joins the group and the new average is 17 years old . what is the value of n ?
"15 n + 37 = 17 ( n + 1 ) 2 n = 20 n = 10 the answer is a ."
divide(subtract(37, 17), subtract(17, 15))