1. First, label the axis on your graph, with units:
time on the x-axis, in units of hours;
distance on the y-axis, in units of miles.
- Draw a graph of distance vs. time. Distance after the first hour = 69 miles, distance after the 2nd hour = 138 miles, etc.
- Observe that this graph is a STRAIGHT LINE with constant slope. Therefore the relationship is PROPORTIONAL.
For every other kind of graph -- i.e. not a straight line -- the relationship is NON-PROPORTIONAL.
Hope this helps.