Answer
\begin{equation}
\Delta T=14.86 K
\end{equation}
also, you can see the following image:
Work Step by Step
The mass of the air satisfies the equation $m=\frac{P V}{R T} \cdot M w T .$
$m=\frac{101.325 k P a \cdot\left(11 m \cdot 8 m \cdot 3 m-35 \cdot 0.075 m^{3}\right) \cdot 28.97 k g / k m o l}{8.314 k P a m^{3} /(k m o l K) \cdot 293 K}=314.96 k g$
The total heat absorbed by the air can be calculated
$Q=35 \cdot 80 J / s \cdot 20 \cdot 60 s=3.36 \cdot 10^{6} J$
Hence
$\Delta T=Q / m C_{v}=14.86 K$
