Reverse range of numbers, scaling

Question

I have a float that goes from 1 to 0 .Im trying to make it so that the order is reversed and scaled so it goes from 0 to -80

Just wondering if there is a straight forward way to do this?

Answer 1

Say that your value is $x$ in a value between 1 and 0. We can reverse the order by taking $1-x$ instead.

Multiply this by $-80$ to get a number from 0 to -80.

In other words:

$$(1-x) \cdot (-80)$$ is in the from 0 to -80.

(The expression can be simplified as $(x-1) \cdot 80$)