Math HW, please help:
At its maximum speed, a motorboat can travel 10 miles downstream on a river in 20 minutes. It takes 30 minutes for the boat to travel back upstream the same 10 miles, also at maximum speed.
Write a system of two equations that could be used to find the maximum speed of the motorboat in still water. Let b represent the maximum speed of the motorboat in miles per hour and let r represent the speed of the river's current in miles per hour. Convert the times into hours. Solve the system of equations for b and r to determine the boat's maximum speed in still water and the speed of the river's current.