Which formula converts Fahrenheit to Celsius?

• A. C = (F - 32) x 9/5
• B. C = (F + 32) x 5/9
• C. C = F - 32 x 5/9
• D. C = (F - 32) x 5/9

Answer: (D)

Converting Fahrenheit to Celsius relies on two ideas: rebaselining the freezing point and scaling the degree size between the two scales. Subtracting 32 from Fahrenheit shifts the freezing point so it lines up at zero, and then multiplying by 5/9 converts the Fahrenheit degree interval (180 degrees from 32 to 212) into the Celsius interval (100 degrees from 0 to 100). The result is C = (F − 32) × 5/9. For example, 212 °F becomes (212 − 32) × 5/9 = 180 × 5/9 = 100 °C, and 32 °F becomes 0 °C. Other forms fail because they either add 32 instead of subtracting, use the reciprocal 9/5 instead of 5/9, or apply the operations in the wrong order, yielding incorrect values.