The average (arithmetic mean) of 20, 40, and 60 is 9 more than the average of 10, 70, and what number? Choose one
A) 15	B) 25	C) 35	D) 13	E) 55

Rationale: "a 1 = 120 / 3 = 40 a 2 = a 1 - 9 = 31 sum of second list = 31 * 3 = 93 therefore the number = 93 - 80 = 13 answer : d"
Answer: D