The formula $C=\frac{5}{9}(F-32)$ can be used to convert from degrees Fahrenheit, $F$, to degrees Celsius, $C$.
a) Solve this formula for $F$.
b) The average high temperature in Paris, France, in May is $20^{\circ} \mathrm{C}$. Use the result in part a) to find the equivalent temperature in degrees Fahrenheit. (www.bbc.co.uk)