A train leaves Little Rock and travels north at 85 kilometers per hour. Another train leaves one hour later and travels north at 95 kilometers per hour. How long after the first train leaves do the trains meet? How far did the trains travel?

Question

cwrw238 · Answer

the distance travelled by the 2 trains is the same
ket first rain take t1 hours and second train t2 hours
speed = distance / time
85 = d / t1   so d = 85t1
95 = d / t2    so d = 95t2
therefore 85t1 = 95t2
also t1 - t2 = 1

solve these 2 equations for  t1, t2 and  then find d

anonymous · Answer

Im not sure how to solve them @cwrw238

cwrw238 · Answer

ok  use  substitution

85t1 = 95t2

so t1= 95t2 / 85  = 19t2 / 17

now plug in 19t2/17  for t2 in the equation t1-t2 = 1:-

19t2 / 17  - t2 = 1

2t2/17 = 1
2t2 = 17
t2 = 8.5 hours

cwrw238 · Answer

and t1 = 1 + 8.5 = 9.5 hours

so its 9.5 hours after the first train leaves when they meet

and the ditance travelled = 85 * 9.5 = 807.5 miles