Question

Can someone explain/help me with this problem?
The speed of the current in a river is 6mph. A ferry operator who works that part of the river is looking to buy a new boat for his business. Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to make this trip in a total of 9 hours. He has a boat in mind, but can only test it in a lake where there is no current. How fast must the boat go on the lake in order for it to serve the ferry operators needs?

Answer 1

set up an equation