A refrigerator absorbs 90 kJ of heat from a cold reservoir a

A refrigerator absorbs 9.0 kJ of heat from a cold reservoir and releases 12 kJ to a hot reservoir. (a) Find the coefficient of performance of the refrigerator. (b) The refrigerator is reversible. If it is run backward as a heat engine between the same two reservoirs, what is its efficiency?

a.Coefficient of performance= Qc / (Qh - Qc) = 9/3 = 3

b. Efficiency = W / Qh = 9/12 = 75%