Question 58603
<pre>At 10Am, adam started out at 60 kilometers per hour to catch tom , who had a
three hour head start. If adam was still 70 kilometers behind at 6 pm, how fast
was tom driving?
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Make this chart
        
         DISTANCE  RATE  TIME
Adam                                          
Tom                            

Let Tom's rate be x.  Fill this in and 
also Adam's rate, which is 60.

         DISTANCE  RATE  TIME
Adam                60                        
Tom                  x      

At 6 pm, Adam had driven since 10AM, 
which is 8 hours.  Tom has a three hour 
head start, so at 6 PM Tom had driven 
for 11 hours. So fill in Adam's and 
Tom's times:

         DISTANCE  RATE  TIME
Adam                60     8                  
Tom                  x    11

Use DISTANCE = RATE × TIME to fill in 
the distances:

         DISTANCE  RATE  TIME
Adam       480      60     8                  
Tom        11x       x    11

Since Adam was 70 km behind Tom at 
6 PM, then

Adam's distance = Tom's distance minus 70

            480 = 11x - 70

Solve that and you'll get that Tom's rate 
is 50 km/h

Edwin</pre>