SOLUTION: 2 towns are 780km apart. 2 super fast trains leave from both the towns at 3pm towards each other at speed of 120km/h and 140km/h. At what time will they pass each other?

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: 2 towns are 780km apart. 2 super fast trains leave from both the towns at 3pm towards each other at speed of 120km/h and 140km/h. At what time will they pass each other?      Log On


   

Question 640960: 2 towns are 780km apart. 2 super fast trains leave from both the towns at 3pm towards each other at speed of 120km/h and 140km/h. At what time will they pass each other?
Found 2 solutions by lwsshak3, josmiceli:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
2 towns are 780km apart. 2 super fast trains leave from both the towns at 3pm towards each other at speed of 120km/h and 140km/h. At what time will they pass each other?
*
let x=distance slower train traveled
780-x=distance faster train traveled
travel time=distance/speed (same for both trains
..
x/120=(780-x)/140
140x=120(780-x)
140x=93600-120x
260x=93600
x=93600/260=360
780-x=420
travel time=360/120=420/140=3 hrs
trains will pass each other at 6 pm

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I think of one train as standing still and the other
traveling at the sum of their speeds
+780+=+%28+120+%2B+140+%29%2At+
+780+=+260t+
+t+=+3+
3 PM + 3 hrs is 6 PM
check:
In 3 hrs, slower train travels
+120%2A3+=+360+ km
faster train travels
+140%2A3+=+420+ km
+360+%2B+420+=+780+ km
OK