10. sue has a boat that would go 9 miles per hour in still water. she travels downstream for a
certain distance and then back upstream to where she stared. sue notices that it takes her 4
hours to travel upstream against the river, and only 2 hours to travel downstream with the
river. the rivers speed is r miles per hour. write and solve for r.

Step-by-step explanation:

In downstream, the speed of the boat will be (9 + r) miles per hour and in upstream the speed of the boat will be (9 - r) miles per hour.

Ratio of the speed in downstream to the speed in upstream is (9 + r):(9 - r).

Hence, the ratio of the time taken by the boat to cover the distance in downstream to upstream is  (9 - r):(9 + r).

triangle and cube

step-by-step explanation: