Each machine at a toy factory assembles a certain kind
of toy at a constant rate of one toy every 3 minutes.
If 40 percent of the machines at the factory are to be
replaced by new machines that assemble this kind
of toy at a constant rate of one toy every 2 minutes,
what will be the percent increase in the number of
toys assembled in one hour by all the machines at the
factory, working at their constant rates?