Question

David and Terri drove a small motorboat down a river with the 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?

Answer 1

speed of boat r mi/hr
speed of currect c mi/hr
speed downstream (c+r) mi/hr
but
distance= 4miles
time=1.5 hours
thus
speed=distance/time
hence:
4/1.5=(c+r)
thus
4=1.5c+1.5r
hence the answer is:
4=1.5c+1.5r