SOLUTION: Car A leaves a certain point travelling at an average rate of 45km/h. Three hours later, Car B leaves the same point travelling at 55km/h in the same direction. After how long will

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Question 683942: Car A leaves a certain point travelling at an average rate of 45km/h. Three hours later, Car B leaves the same point travelling at 55km/h in the same direction. After how long will Car B over take Car A?
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Car A leaves a certain point travelling at an average rate of 45km/h. Three hours later, Car B leaves the same point travelling at 55km/h in the same direction. After how long will it take for Car B to overtake Car A?
How to do it, first without algebra and second, using algebra:

Without using any algebra:

Three hours later, car A has a 45×3 or 135 km head start.  Car B's 
approach rate is 55-45 or 10km/h and so it'll take car B 135÷10 or 13.5
hours to catch up to car A.

With algebra.  Let car B's time be x, then car A's time is 3 hours more
or x+3. Then we fill that in as well as the given rates:

         rate     time       distance
Car A     45       x+3        
Car B     55        x

Then we use rate·time = distance

         rate     time       distance
Car A     45       x+3        45(x+3)        
Car B     55        x          55x

Since both cars eventually went the same distance we
set the two distances equal to each other:

        45(x +  3) = 55x
         45x + 135 = 55x
              -10x = -135
                 x = %28-135%29%2F%28-10%29
                 x = 13.5 hours

Your teacher will probably insist that you do it by algebra.

Edwin