Description: Sal uses a linear equation to model the amount of snow on the ground. Created by Sal Khan and Monterey Institute for Technology and Education. On Monday morning, there were 12 inches of snow on the ground. So they're essentially saying that we had 12 inches of snow on the ground on Monday and that every day after that, two inches melted. And what they say is create an equation and a graph to show the relationship between the day and the amount of snow on the ground.*Teacher Advisor is 100% free.