[tex]54.7^{\circ}\:F[/tex]
1) As we can see in this question, a formula has already been given. So, let's make use of it to convert the temperature from Celsius to Fahrenheit degrees:
[tex]F=\frac{9}{5}C+32[/tex]
2) Note that we want to know Fahrenheit, so we'll use the second one from top to bottom and plug into that the temperature in Celsius:
[tex]\begin{gathered} F=\frac{9}{5}(12.6)+32 \\ \\ F=\frac{9}{5}\cdot \:12.6+32 \\ \\ F=\frac{113.4}{5}+32 \\ \\ F=\frac{32\cdot\:5+113.4}{5} \\ \\ F=\frac{160+113.4}{5} \\ \\ F=\frac{273.4}{5} \\ \\ F=54.68\approx54.7 \\ \\ \end{gathered}[/tex]
Note that we had to round it off to the nearest tenth as requested.