###### Example2.1.5

The expression:

\begin{equation*} \frac{5}{9}(F - 32) \end{equation*}

can be used to convert from degrees Fahrenheit to degrees Celsius. To do this, we need a Fahrenheit temperature, $$F\text{.}$$ Then we can evaluate the expression. This means replacing its variable(s) with specific numbers and calculating the result. In this case, we can replace $$F$$ with a specific number.

Let's convert the temperature 89 °F to the Celsius scale by evaluating the expression.

\begin{align*} \frac{5}{9}(F - 32) \amp= \frac{5}{9}(\substitute{89} - 32)\\ \amp= \frac{5}{9}(57)\\ \amp= \frac{285}{9}\approx 31.67 \end{align*}

This shows us that 89 °F is equivalent to approximately 31.67 °C.

in-context