Pulley system, demonstrating how pulleys facilitate the lifting of heavy weights (2004)
(upload.wikimedia.org)
No, the other commenters are right — it's between 100 and 150 depending on the angle. And it's like this because we have 50 N + 50 N on both sides of the top pulley (classic pulley thing) + 50 N more attached to it at the bottom. Kinda confusing at first, not gonna lie :)