The average (arithmetic means) of t and y is 15, and the average of w and x 15. What is the average of t, w, x, and y?

Question

(A) 7.5
(B) 15
(C) 22.5
(D) 30
(E) 60

Answer 1

t + y = 15
t + y / 2 = 15
2 * t + y / 2 = 15 *2
t + y = 30

w + x = 15
w + x / 2 = 15
2 * w + x / 2 = 15 * 2
w + x = 30

t + y + w + x / 4
30 + 30 / 4
60 / 4
15