posted by Anon .
Fahrenheit and Celsius are two measures of temperature. The temperature in degrees Celsius is equal to five ninths of 32 less than the temperature in degrees Fahrenheit. What is a function rule that represents this situation?
Draw a vertical line, calling the left side F for Fahrenheit, and the right side C for Celsius
Consider the top of the line to be the boiling point of water and the bottom the freezing point of water
On the C side, mark the top 100 and the bottom 0, (very logical)
On the F side, mark the top 212 and the bottom 32, (totally illogical)
pick any arbitrary point on the line, calling the left F and the right side C
Now create a proportion and solve it
(F - 32))/(212 - 32) = C/100
(F-32)/180 = C/100
100F - 3200 = 180C
100F = 180C + 3200
F = (180/100)C + 32
F = (9/5)C + 32
or after rearranging:
C = (5/9)(F - 32)