SOLUTION: At 1:00 pm a motorbike heading north and travelling at an average speed of 75km/h passes a bus heading south and travelling at an average speed of 65km/h. At what time will they be

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Question 947551: At 1:00 pm a motorbike heading north and travelling at an average speed of 75km/h passes a bus heading south and travelling at an average speed of 65km/h. At what time will they be 21 km apart?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You can just add the speeds to get the distance
and time elapsed between them
Let +t+ = time in hrs
+21+=+%28+75+%2B+65+%29%2At+
+21+=+140t+
+t+=+3%2F20+
Convert to minutes
+%28+3%2F20+%29%2A60+=+9+
At 1:09, they will be 21 km apart