# Thermal Efficiency in a Reversible Process

A quantity of perfect monoatomic gas is performing the reversible cycle in the figure. If the thermal efficiency of this cycle can be written as $$\eta=\dfrac{a}{b}$$, where $$a$$ and $$b$$ are coprime positive integers, what is the value of $$a+b$$?

• The molar specific heat at constant volume is: $${C}_{V}=\frac{3}{2}R$$.
• Thermal efficiency is defined as the ratio of heat input to work output, i.e. $$\eta=\frac{W}{Q_\textrm{in}}$$.
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