SOLUTION: Train A leaves a station traveling at 20 mph. Four hours later train B leaves the same station traveling in the same direction at 30 mph How long does it take for train B to catch

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Question 565784: Train A leaves a station traveling at 20 mph. Four hours later train B leaves the same station traveling in the same direction at 30 mph How long does it take for train B to catch up to train A?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Train A leaves a station traveling at 20 mph.
Four hours later train B leaves the same station traveling in the same direction at 30 mph
How long does it take for train B to catch up to train A?
:
Let t = travel time of train B when it catches A
then
(t+4) = travel time of train A when it's caught
:
When this occurs they will have traveled the same distance.
Write a distance equation: dist = speed * time
:
30t = 20(t+4)
30t = 20t + 80
30t - 20t = 80
10t = 80
t = 80/10
t = 8 hrs for B to catch A
:
:
Confirm this by finding the distance of each train
30*8 = 240 mi
20*12 =240 mi