The average of 2x and y is 47. The average of 2z and y is 31. What is the average of x, y, and z ?
(2x + y)/2 = 47
2x + y = 94
(2z + y)/2 = 31
2z + y = 62
add them up
2x + 2y + 2z = 156
x+y+z = 78
average of x, y, and z
= (x+y+z)/3
= 78/3 = 26