The output of the machine is
(output work) = (output force) x (distance)
450 N-m = (output force) x (3 meters)
Divide each side
by 3 meters: Output force = (450 N-m) / (3 m)
= 150 newtons .
With all the information given about the output work, we don't need
to know anything about the input work, or even the fact that we're
dealing with a machine.
It's comforting, though, to look back and notice that the output work
(450 N-m) is not more than the input work (500 N-m). So everything
is nice and hunky-dory.
___________________________________
Well, my goodness !
I didn't even need to go through all of that.
Given:
-- The input force to the machine is 50 newtons.
-- The mechanical advantage of the machine is 3 .
That right there tells us that
-- The output force of the machine is 150 newtons.
We don't need any of the other given information.