The ratio of the number of skiers who bought season passes to the number of snowboarders is 9:6. If a total of 225 people bought season passes, how many snowboarders bought season passes?
The total number of "ratio units" is 9+6 = 15, so each one must stand for 225/15 = 15 people. Then 6·15 = 90 people were snowboarders who bought season passes.
