David and Terri drove a small motorboat down a river with a current. The rate the boat traveled in still water was r miles per hour, and the current's average speed was c miles per hour. It took them 1.5 hours to travel 4 miles downstream. Which of the following equations can be used to represent this information? a. 1.5 = (r + c)4 b. 1.5 = (r - c)4 c. 4 = (r + c)1.5 d. 4 = (r - c) 1.5

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anonymous · Answer

What was their effective speed?