Well lets say y = the amount of medals won. lets say x is the amount won by short people and z is the amount won by tall. we know that the total medals is the total medals won by short and tall so: y = x + z
it says that tall people are 3.times more likely. this would mean they won three times more than short people. so z = 3x.
so if we know what z equals, we can replace z with what it is equal to. so: y = x + z y = x + 3x y = 4x
we know that 60 medals were won so y = 4x 60 = 4x x = 15