The sum of three numbers $a, b$ and $c$ is 60. If we decrease $a$ by 7, we get the value $N$. If we increase $b$ by 7, we get the value $N$. If we multiply $c$ by 7, we also get the value $N$. What is the value of $N$?
+37170 x -7 + (x+7) + x/7 = 60
15/7 x = 60
= 28 so the numbers are 21 35 and 4 and N = 28
