Writing and Graphing Proportional Relationships

Suppose you start with $0 and earn or lose money at a constant rate. Here, [br][br][i]x[/i] = number of minutes[br][i]y[/i] = the amount of money you have (balance) after [i]x[/i] minutes
Write an equation that models the scenario described below. Then drag the LARGE WHITE POINTS to graph this scenario.

Information: Writing and Graphing Proportional Relationships