Posted by
**lee** on
.

please explain the step for this I have no idea.

the speed of the current in a river is 6 mph a ferry operator who works that part of the river is looking to buy a new boat for his business everyday his route takes him 22.5 miles against the current and back to his deck and he needs this trip in a total of 9 hours he has a boat in mind but he can only test it on a lake where there in no current how fast must the boat go on the lake in order for it to serve the ferry operators needs.

This is what I got;

22.5/(x+6)+22.5/(x-6)=9

x=9mph