I have this exercise that i don't know how to solve.

We assume that the conditions for this excersie is at 20 Celcius

density of the air: 1.1881(kg/m³)

Specific heat : 1007 J/kg*k

Temperature | density of the air | specific heat of the air

.

The data obtained in a pin heat exchanger is shown in the following table:

Calculate the efficiency of the pinned heat exchanger:

\begin{tabular}{|c|c|c|} \hline Temperatura(C) & Densidaddelaire(kg/m3) & Calorespecficodelaire(J?k.K.) \\ \hline 20 & 1.1881 & 1007 \\ \hline 40 & 1.1120 & 1008 \\ \hline \end{tabular} \begin{tabular}{|l|l|l|l|} \hline ST-1 & ST-7 & SC-1(L/min) & SW-1(W) \\ \hline 21.705 & 20.02 & 158.6385 & 4.76 \\ \hline \end{tabular} \begin{tabular}{|c|c|c|} \hline Temperatura(C) & Densidaddelaire(kg/m3) & Calorespecficodelaire(J?k.K.) \\ \hline 20 & 1.1881 & 1007 \\ \hline 40 & 1.1120 & 1008 \\ \hline \end{tabular} \begin{tabular}{|l|l|l|l|} \hline ST-1 & ST-7 & SC-1(L/min) & SW-1(W) \\ \hline 21.705 & 20.02 & 158.6385 & 4.76 \\ \hline \end{tabular}