将值从一个函数移动到另一个函数

I am new to javascript and I am trying to learn the programming language. I created a quick website that converts temperature from fahrenheit to Celsius and I am using javascript to do the conversion. I know that it does not have to be broken into two different functions but I though I would start simple and build towards more complex. The code I am using to complete the conversion is:I am new to javascript and I am trying to learn