It takes 2 hours for the ship to go back and forth from Port A to Port B, and when it comes back, it travels 8 kilometers per hour more than when it went, so it travels 6 kilometers more than 1 hour in the second hour. What is the distance between port A and port B?

Solution: set the speed to x and return to x+8; The distance between the two ports is y kilometers (one side)

There is a quadratic equation with one variable.

Y/x (time to go) +y/(x+8) (time to return) = 2.

(y/x-1)*x=6/2=3 (according to the condition: the second hour is 6 kilometers more than 1 hour).

Y= 15 x= 12 of the solution.

Then the distance between the two ports is 15km.