Take -5x + 3x = -2x
because there is a -3x and a 3x they cancel each other out.
and the -17 is left
-2x = -17
divide -2 by -17 = 8.5
He would have done 10+10+10 like for each stick then + How ever many ones there were and then we would have done the same for the other set . Soorry if I'm wrong
I think all of them are true