14.44 degrees
Explanation
Step 1
Let
[tex]\text{temperature in the nigthtime=temperature in the afternoon plus increase}[/tex]then
temperature outside is the afternoon=4.7
increase=9.74
now, replace
[tex]\begin{gathered} \text{temperature in the nigthtime=temperature in the afternoon plus increase} \\ \text{temperature in the nigthtime=4}.7+9.74 \\ \text{temperature in the nigthtime=14.44} \end{gathered}[/tex]so, the answer is 14.44 degrees
I hope this helps you