Can someone help me with this question with work shown. Thank you!

An engine using 1 mol of an ideal gas ini- tially at 16 L and 259 K performs a cycle consisting of four steps: 1) an isothermal expansion at 259 K from 16 L to 36.4 L; 2) cooling at constant volume to 145 K : 3) an isothermal compression to its original volume of 16 L; and 4) heating at constant volume to its original temperature of 259 K . Find its efficiency. Assume that the heat capacity is 21 J/K and the univer- sal gas constant is 0.08206 L - atm/ mol/K = 8.314 J/mol/K. Give your answer in the form of a percentage