The biggest giveaway here is the other answers have<em> </em>+ a whole number at the end of the equation. We would see this + as a y-intercept on the graph.
Since our line had no y-intercept and starts from zero, y =15x can be used to represent the graph shown
Another way to know this is to look at the points marked on the line. There is a point at (2, 30). By plugging these co-ordinated into y = 15x we get 30 = 30, which makes sense
