The answer is 35 miles per day because the equation to find slope is rise over run.
To do rise over run, select two points on the graph. On this graph, it is easy to pick (0,0) and (3,105). Divide how much the line has risen, 105, by how much it has run on horizontally, 3, to get 36 miles per day.
We also know that it isn't the second answer, 35 miler per hour, because the unit of the x-axis is days. Hope this helps!
