Finding the biggest number from one-randomly generated and two-prompted in JavaScript

everyone. I'm new in coding and trying to make my way through..

I have a task to write a program, that will find the biggest number from 3 numbers and will display it with certain conditions.

1. If the number is bigger than 70, then it should be reduced on 10% and if it bigger than 40, reduced on 5% if it bigger than 10, reduced on 2%. enter image description here