16Hit1600
AlgebraHardRearranging a conversion formula

Algebra practice question

The formula C = (5/9)(F − 32) converts a temperature F in degrees Fahrenheit to C in degrees Celsius. Which equation gives F in terms of C?

  1. A. F = (9/5)C + 32Correct
  2. B. F = (5/9)C + 32
  3. C. F = (9/5)(C + 32)
  4. D. F = (9/5)C − 32

Answer: A. F = (9/5)C + 32

Multiply both sides by 9/5: (9/5)C = F − 32. Then add 32: F = (9/5)C + 32. Check: C = 100 gives F = 180 + 32 = 212.

Why the other answers are wrong

B. F = (5/9)C + 32
The 5/9 must be inverted when it moves to the other side: multiply by 9/5.
C. F = (9/5)(C + 32)
The 32 is added AFTER multiplying, not inside the parentheses; (9/5)(C + 32) at C = 100 gives 237.6.
D. F = (9/5)C − 32
F − 32 = (9/5)C means F = (9/5)C + 32; the 32 is added, not subtracted.

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