SOLUTION: the distance between two place on road A and B is 70 km. the A car starts from A and other from B. if they travel in the same direction, they will meet after 7 hours. if they tra

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: the distance between two place on road A and B is 70 km. the A car starts from A and other from B. if they travel in the same direction, they will meet after 7 hours. if they tra      Log On


   

Question 1095787: the distance between two place on road A and B is 70 km. the A car starts from A and other from B. if they travel in the same direction, they will meet after 7 hours. if they travel towards each other they will meet after 1 hour, then find their speed
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
f= speed of the faster car, in km/h
s= speed of the slower car, in km/h
system%28f%2Bs=70%2F1%2Cf-s=70%2F7%29 system%28f%2Bs=70%2Cf-s=10%29


f-s=10 f=s%2B10

system%28f%2Bs=70%2Cf=s%2B10%29 s%2B10%2Bs=70

2s%2B10=70 2s=70-10 2s=60 s=60%2F2 s=30

system%28s=30%2Cf=s%2B10%29 highlight%28system%28s=30%2Cf=40%29%29

EXPLANATION
When traveling towards each other,
they reduce the distance between them at a rate of 70km%2F%221+hour%22 , so
s%2Bf=70%2F1 --> s%2Bf=70
If both cars travel in the same direction,
the distance between them will change (increase or decrease)
as a rate of 70km%2F%227+hours%22=%2210+km+%2F+h%22 .
If the faster car was running away from the slower one,
they would bm never meet,
so if they meet in 7 hours,
the faster car is chasing the slower one.
The distance between will be decreasing at a rate of
f-s=10 .
So, we have to solve the system
system%28f%2Bs=70%2Cf-s=10%29 .