Get 60 by subtracting 30 from 90 because the angle is a right angle. Since b is identical to a and also is a right triangle, it will also be 60. Get c as 30 by looking at its vertical angle across from it.
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.
