Tension T1 in the string passing over the pulley A is given as
2T1 = L or T1 = L/2
Tension T2 in the string passing over the pulley B is given as
2T2 = T1 or T2 = T1/2 = L/22
Tension T3 in the string passing over the pulley C is given as
2T3 = T2 or T3 = T2/2 = L/23
In equilibrium, T3 = E
E = L/23
Mechanical advantage = MA = L/E = 23
As one end of each string passing over a movable pulley is fixed, so the free end of string moves twice the distance moved by the movable pulley.
If load L moves up by a distance x, dL = x, effort moves by a distance 23x, dE = 23x
Velocity Ration VR = Distance moved by the effort dE/Distance moved by the load dL = 23 x/X = 23
Efficiency = MA/VR = 23/23 = 1 OR 100%