Combining rates - upstream, downstream in {time, distance} plane

This applet is a workbench for the exploration of all upstream-downstream problems. It opens with the solution to the following problem - An airplane can fly 3000 miles in 6 hours if there is no wind. It can fly that distance in 7.5 hours when it flies against the wind. It can fly that distance in 5 hours when it flies with the wind. How fast does the wind blow?
- GOING FURTHER 1. Use this applet to generate several different upstream-downstream problems. 2. Compare this applet to "Combining rates I - Joe & Sam paint a wall. How is it similar? different?