What is the formula for me to get a value at a certain point?

Question

I have a two linear points : 400 and 1000. At 400, the value is 150. But for 1000, I want the value to be 100.

So in 600 steps (1000-400), the value has to go down by 50(150-100). I'm not really sure where I should go from here and what to do with these values.

Answer 1

You need the two-point form of a linear equation. If $x$ is your input and $y$ is your output you have $$y-150=-50\cdot\frac{x-400}{1000-400}$$ Plug your points in and see that it works. I left it unsimplified so you can see where the numbers come from if you read the article.