SOLUTION: Can you please help me with this problem. I am totally confused when it comes to D=RT word problems. A local commuter train leaves downtown at 5 pm. And express commuter train

Click here to see ALL problems on Travel Word Problems

Question 284235: Can you please help me with this problem. I am totally confused when it comes to D=RT word problems.
A local commuter train leaves downtown at 5 pm. And express commuter train leaves downtown at 5:30 pm. The express train travels twice as fast as the local, so the local has to pull over on a siding to avoid a crash 45 miles from downtown. At what time would the crash occur? How fast is each train going?
Thanks for your help!
Christine
Answer by scott8148(6628) (Show Source):
You can put this solution on YOUR website!
the distance for both trains is 45 mi
the time for the local train is 1/2 hr longer ___ for the times to be equal, this must be subtracted
the speed of the express is twice the speed of the local

time equals distance divided by rate

45 / 2r = (45 / r) - (1/2)

45 = 90 - r ___ r = 45 (this is the speed of the local train)

2r = 90 (this is the speed of the express train)

the travel time to the "crash" site is 1/2 hr for the express and 1 hr for the local
___ so the crash time is 6:00 pm