The speed of a certain boat in still water is 20 kilometers per hour, and the speed of river water is 5 kilometers per hour. It took the boat 8 hours to go back and forth between AB and AB ports. How many kilometers is the distance between AB and AB ports?
某船的静水速度每小时20公里，河水速度每小时5公里，这船往返于AB两港共花了8小时，问AB两港相距多少公里？
<result>75</result>