At which temperature are Fahrenheit and Celsius equal?

The correct answer is option 2. \(-40\)

To find the temperature at which Fahrenheit and Celsius are equal, we can use the conversion formula:

\[°F = \frac{9}{5} °C + 32\]

We can set °F equal to °C and solve for the temperature:

\[°C = \frac{9}{5} °C + 32\]

Subtracting \( \frac{9}{5} °C \) from both sides:

\[0 = \frac{9}{5} °C - °C + 32\]

\[0 = \frac{4}{5} °C + 32\]

Subtracting 32 from both sides:

\[-32 = \frac{4}{5} °C\]

To solve for \( °C \), multiply both sides by \( \frac{5}{4} \):

\[°C = -32 \times \frac{5}{4}\]

\[°C = -40\]

So, the temperature at which Fahrenheit and Celsius are equal is \( -40 \) degrees.

Therefore, the correct option is: 2. -40