Question 1164836
Sean drove at a uniform speed of 90km/h. He started driving at 5:30 am and
reached his destination at 1.30 pm. Mary started driving at the same time as
Sean and reaches the same destination in 6 hrs. How far was Sean from his
destination when he was 150 km apart from Mary?
<pre>
Sean drove From 5:30 AM till 1:30 PM, so he drove for 8 hours.
Since Sean drove for 8 hours at 90 km/h, that means that the distance to the
destination was 90∙8 = 720 km.

Mary drove for 6 hours from 5:30 AM and got to the same place at 11:30 AM. 
So her speed was 720/6 = 120 km/h

So their rate of separation was the difference in their speeds.
So they separated at 120-90=30 km/h

Let's find the time at when they were 150 km apart (when they had separated
by 150 km):

time = (separation distance)/(separation rate) = 150/30 = 5 hours

So Sean had driven 5 hours when he was 150 km behind Mary.
Since Sean's rate was 90 km/h, he had driven 90∙5 = 450 km.

Since the distance to the destination was 720 km, Sean was 720-450=270 km
from his destination.

Answer: Sean was 270 km from his destination when he was 150 km apart from
Mary
------------------
Analysis: Sean was the slower driver.  They left at 5:30.  Their destination
was 720 km away.  5 hours later at 10:30 AM, Sean was 450 km from the
starting point and 270 km from the destination. They were 150 km apart,
Mary was 600 km from the starting point and 120 km from the destination.
Mary arrived at the destination at 11:30, and Sean arrived 2 hours later at  
1:30 PM.

Edwin</pre>