Question

To change Fahrenheit temperatures to Celsius temperatures, you can use the formula C = 5/9(F – 32). Which answer is the best first step to solve the equation for F?
A. Add 32 to both sides.
B. Subtract F from both sides.
C. Multiply both sides by 9/5.
D. Divide both sides by F.

Answer 1

C. Multiply both sides by 9/5.

C = 5/9(F – 32)

We want to isolate F, which means we need to get F alone.

The quantity in the parentheses is multiplied by 5/9.  We need to do the opposite, or multiply by the reciprocal to isolate the parentheses

9/5 C = 9/5* 5/9(F – 32)

9/5 C = F-32

This is the first step in isolating, or solving, for F