



 
Hi Fran, The key to both of these problems is the units. In both instances the rate is in km/hr so
For Kim's problem suppose that the rate she travels in still water is r km/hr. Thus paddling upstream her rate is (r  2) km/h and on the return trip her rate is (r + 2) km/h. Use equation (1) to write an expression for the time for each of the two legs of the trip and then add these times to get 3.75 h. Solve for r. Use equation 1 to find an expression for the time it took Olivia to drive x km at 60 km/h? I hope this helps,  


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