To express this situation let x be the number of rides you take in the hot fair. 
To x we have to multiply the cost of each ride and add the cost of admission to the fair, this can be writeen as 

Since you can expend a maximum of 35, the inequality representing this problem is 

Solving the inequality we have 

Since we can't take a decimal part of a ride, the maximum number of rides you can take is 12.