First sketch the process on `P-V` diagram.
Let initial thermodynamic coordinates are `(P_0,V_0,T_0)`
`DeltaW_(cyclic)=P_0V_0=3RT_0`
`DeltaQ_(1rarr2)=nC_V(T_2-T_1)=3.(3R)/(2)(2T_0-T_0)=(9RT)/(2)`
`DeltaQ_(2rarr3)=nC_P=(T_3-T_2)=3.(5R)/(2)(4T_0-2T_0)`
`=15RT_0`
`DeltaQ_(3rarr4)=-ve`,`DeltaQ_(4rarr1)=-ve`
Efficiency `eta=(DeltaW_(cyclic))/("Heat supplied")=(DeltaW_(cyclic))/(DeltaQ_(1rarr2)+DeltaQ_(2rarr3))`
`=(3RT_0)/((9)/(2)RT_0+15RT_0)=(6)/(39)=(2)/(13)`
`eta=(2)/(13)xx100=(200)/(13)%`