The real numbers $x$, $y$ and $z$ satisfy the equations $x + 2y + 3z = 950$ and $3x + 2y + z = 1450$. What is the average of $x$, $y$ and $z
Add the two equations together. Divide both side of the result by 4 to get x+y+z, then divide by 3 to get the average.
+589 
