PULLEYS AND COMPOUND PULLEY SYSTEM.

In a system of pulleys, the equilibrium between te forces depends on te path that the rope follows.
PULLEYS: There are two basic types:
FIXED PULLEY: The forces are equal because the rope moves the same distance on both sides. 

F:R (Force: Resisrtance)

MOVABLE PULLEY: The rope follows a double path around the pulleys. We need half the force to lift the same weight as with a fixed pulley.

F: R/2 (Force: Resistance/2)