A car rental company charges a flat fee of $30$ dollars to rent a car. In addition to that you have to pay a daily fee. If you keep the car for $5$ days or less, it costs $25$ dollars per day. If you keep the car longer than $5$ days, it costs $20$ dollars for each additional day. Given that Steven paid $275$ dollars for renting a car, how long could he keep the car? 
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