The real numbers x, y and z satisfy the equations x+2y+3z=950 and 3x+2y+z=450 . What is the average of x, y and z ?

Add the two equations together to get

4x + 4y + 4z = 1400 divied by 4

x + y + z = 350 now divide by 3 to get the average of x , y and z............