You can 
put this solution on YOUR website! 
Cost equation for daily pass:  
    C_daily = 67x + 25x = 92x,  where x = # days skied
Cost equation for season pass:
    C_season = 350 + 25x
We wish to find x such that C_season < C_daily
   350 + 25x < 92x
       350   < 67x
       350/67 < x    
        5.224 < x     
    x = 6 ski days
Sanity check...
#days skied     Daily pass cost     Season pass cost
    4             368                   450
    5             460                   475
    6             552                   500    <----  Season pass becomes cheaper
If you plot the two cost equations, the point where they cross is the point where the season pass becomes more cost effective (well, the nearest integer above where they cross).   
The green line represents the season pass cost equation:
