SOLUTION: shelly and jack left from the same place at the same time and drove in opposite directions along a straight road. Jack traveled 15 miles per hour faster than shelly. After 3 hours,

Question 175275: shelly and jack left from the same place at the same time and drove in opposite directions along a straight road. Jack traveled 15 miles per hour faster than shelly. After 3 hours, they were 315 miles apart. Find the rate at which each traveled.
Answer by agosset(4) (Show Source): You can put this solution on YOUR website!
We know that Speed equals distance over time

In this problem we are dealing with two speeds, Shelly's and Jack's
And we know that Jack's speed is 15 miles faster:
Jack's (J) = Shelly's (S) + 15

Then we know they have covered 315 miles (distance) after 3 hours (time)using their combined speeds.
Since they are traveling opposite directions we need to add their speeds:

We replace the known values for distance and speed:

Remember that J=S+15 so we replace J with the expression s+15

And we know that Jacks is 15 more

Jack's speed= 60 Miles per hour
Rate= Speed
Jacks= 60 Miles per hour
Shelly's = 45 Miles per hour

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