\(\frac{Q_{\text {in }}}{Q_{\text {ott }}}=\frac{T_{\text {in }}}{T_{\text {out }}}\) \(....(I)\)
Substitute \(500 Q_{\text {in }}, 400\) for \(T_{\text {in }} 300\) for \(T_{\text {old }}\) in equation \((I).\)
\(\frac{500}{Q_{\text {out }}}=\frac{400}{300}\)
\(Q_{\text {out }}=375 \;J\)