\(\eta=1-\frac{{T}_{2}}{{T}_{1}}\)
\(\frac{1}{4}=1-\frac{{T}_{2}}{{T}_{1}}\)
\(\frac{{T}_{2}}{{T}_{1}}=\frac{3}{4} \ldots\) \((i)\)
\(\frac{1}{2}=1-\frac{{T}_{2}-58}{{T}_{1}}\)
\(\frac{{T}_{2}}{{T}_{1}}-\frac{58}{{T}_{1}}=\frac{1}{2}\)
\(\frac{3}{4}=\frac{58}{{T}_{1}}+\frac{1}{2}\)
\(\frac{1}{4}=\frac{58}{{T}_{1}} \Rightarrow {T}_{1}=232\)
\({T}_{2}=\frac{3}{4} \times 232\)
\({T}_{2}=174\, {K}\)