A girl buys a monthly bus​ pass, which entitles her to unlimited bus​ travel, for ​$40 per month. Without the pass each bus ride costs ​$1.60. How many rides per month would she have to take so that the cost of the rides without the bus pass is equal to the total cost of the rides with the bus​ pass?
The number of rides at which the unlimited ride pass equals the cost of individual ride purchases is ?.