If a system requires 150 J of input work and produces 123 J of output work, what's its efficiency?

The efficiency of work is a dimensionless value, and is equivalent to the ratio of the actual work output to the theoretical work requirement. This can be calculated using the equation:

Efficiency = (actual work) / (work requirement) = 123/150 = 0.82

The higher the efficiency, the better performance is given by the system. In reality, efficiency is always lower than 1 which is the ideal value.