Why is -40 degrees Fahrenheit equal to -40 degrees Celsius?

• A. Because -40 is the lowest temperature possible in both scales.
• B. Because the conversion formula between Fahrenheit and Celsius results in the same value at -40.
• C. Because the difference between the two scales is always 40 degrees.
• D. Because both scales are based on the freezing point of water.

Answer: (B)

Verified step by step guidance

1. Recall the formula to convert Fahrenheit (F) to Celsius (C): \(C = \frac{5}{9} (F - 32)\).
2. Set the Celsius temperature equal to the Fahrenheit temperature to find the point where they are the same: \(C = F\).
3. Substitute \(C\) with \(F\) in the conversion formula: \(F = \frac{5}{9} (F - 32)\).
4. Multiply both sides of the equation by 9 to eliminate the denominator: \(9F = 5(F - 32)\).
5. Expand and solve for \(F\): \(9F = 5F - 160\), then rearrange to isolate \(F\) and find the temperature where both scales are equal.