How Do You Derive Temperature Conversion Formulas?

[briteliner]

Homework Statement

the fahrenheit temp scale is defined to that ice melts at 32 F and water boils at 212 F. Derive formulas for converting fahrenheit to celsius and back.

Homework Equations

c=5/9(f-32)

The Attempt at a Solution

ok so i figured that 212-32= 180
and
100-0=100
so the ratio of c/f= 5/9
i don't know how to get the 32 part into the equation

 

[Dick]

0C=32F. So a fahrenheit temperature f is (f-32) fahrenheit degrees above 0C. Now just convert the (f-32) fahrenheit degrees to celsius degrees.