These Tires Don't Last Long
Albert is driving a scooter. He brings a spare tire. A tire can last for 5 kilometers. How many km can Albert travel with these tires?
Assumption: A scooter needs two tires. Albert's scooter already has two tires, so with the spare tire there are three tires. All of them are new when Albert begins his journey. Albert can change his tire configuration at any time.