Self graphed in point slope form

I am trying to create a Desmos activity where students have to put in the point slope form of an equation and the line shows up based on the inputted equation. I am having trouble getting the line to graph.

Problem Desmos

At the moment, you have numbers m and b being sent through to the graph from the equation that students enter, but you aren’t doing anything with those in the graph itself.

If you include something like f(x)=mx+b in the graph, the line will show up as expected.