If w + x = - 4, x + y = 25 and y + w = 15, then the average of w, x, y, is:

Question: If w + x = - 4, x + y = 25 and y + w = 15, then the average of w, x, y, is:

Solution:
Given that,
w + x = - 4 ...... (1)
x + y = 25 ...... (2)
and y + w = 15 .....(3)

Adding all three equations,
(w + x) + (x + y) + (y + w) = - 4 + 25 + 15
⇒ 2(w + x + y) = 36
⇒ w + x + y = 36/2
∴ w + x + y = 18

Therefore, the average of w, x, y is = (w + x + y)/3 = 18/3 = 6