\({W}_{{A}}=1-\frac{{Q}_{2}}{{Q}_{1}}=1-\frac{{T}}{{T}_{1}} \Rightarrow \frac{{Q}_{2}}{{Q}_{1}}=\frac{{T}}{{T}_{1}}\)
\({W}_{{B}}=1-\frac{{Q}_{3}}{\left({Q}_{2} / 2\right)}=1-\frac{{T}_{3}}{{T}} \Rightarrow \frac{2 {Q}_{3}}{{Q}_{2}}=\frac{{T}_{3}}{{T}}\)
Now, \({W}_{{A}}={W}_{{B}}\)
\({Q}_{1}-{Q}_{2}=\frac{{Q}_{2}}{2}-{Q}_{3}\)
\(\Rightarrow \frac{2 {Q}_{1}}{{Q}_{2}}+\frac{2 {Q}_{3}}{{Q}_{2}}=3\)
\(\Rightarrow \frac{2 {T}_{1}}{{T}}+\frac{{T}_{3}}{{T}}=3\)
\(\frac{2 {T}_{1}}{3}+\frac{{T}_{3}}{3}={T}\)