Description: Sal solves an interesting application problem using a linear model. Created by Sal Khan and Monterey Institute for Technology and Education. The number of dollars she has left, y, after x days, is approximated by the formula y is equal to 40 minus 2.5x. Graph the equation and use the graph to estimate how much money Jill will have 8 days later. Then we can use that table to actually plot the graph.*Teacher Advisor is 100% free.