SOLUTION: please help me with this word problem: Two stations A and B are 90km apart and on a highway.A car starts from A and another from B at the same time.If they go in the same directio

Algebra ->  Linear-equations -> SOLUTION: please help me with this word problem: Two stations A and B are 90km apart and on a highway.A car starts from A and another from B at the same time.If they go in the same directio      Log On


   

Question 749355: please help me with this word problem:
Two stations A and B are 90km apart and on a highway.A car starts from A and another from B at the same time.If they go in the same direction, they meet after 9 hours and if they go in opposite directions,they meet after 1 2/7 (one- two by seven hours)hours, find the speeds of both the cars.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Two stations A and B are 90km apart and on a highway.
A car starts from A and another from B at the same time.
If they go in the same direction, they meet after 9 hours and
if they go in opposite directions, they meet after 1 2/7 hours,
find the speeds of both the cars.
:
Change 1 2/7 hrs to 9/7 hrs
:
Let x = Car from A's speed
Let y = Car from B's speed
:
A distance equation when going towards each other
9%2F7x + 9%2F7y = 90
multiply by 7
9x + 9y = 630
:
A distance equation when going the same direction
9x = 9y + 90
9x - 9y = 90
:
Use elimination here
9x + 9y = 630
9x - 9y = 90
---------------addition eliminates y, find x
18x = 720
x = 720/18
x = 40 km/hr speed of the Car from A
then
9(40) + 9y = 630
9y = 630 - 360
9y = 270
y = 270/9
y = 30 km/hr speed of the car from B
:
:
You can confirm this
9(40) - 9(30) = 90