SOLUTION: Joe and louise are making a drive from San Diego to Salt Lake city. After 4 hrs of driving they r 507 miles from salt lake city. 8 hrs into their trip they r only 267 miles away f

Algebra ->  Graphs -> SOLUTION: Joe and louise are making a drive from San Diego to Salt Lake city. After 4 hrs of driving they r 507 miles from salt lake city. 8 hrs into their trip they r only 267 miles away f      Log On


   

Question 836316: Joe and louise are making a drive from San Diego to Salt Lake city. After 4 hrs of driving they r 507 miles from salt lake city. 8 hrs into their trip they r only 267 miles away from their destination. Assume they averaged the same speed for the entire trip.
? I'm trying to get the expression for this problem.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
The speed is the same for the whole trip, so this stays constant.
Let d = distance from San Diego to Salt Lake City.

4 hours, traveled d-507 miles;
8 hours, traveled d-267 miles.

What is the distance traveled between the 8 hour completion and the 4 hour completion?
%28d-267%29-%28d-507%29=-267%2B507=240 miles.

From 4 hours to 8 hours time completion is a 4 hour time quantity.
We can find the value for the constant speed now.
%28240%2F4%29%28miles%2Fhour%29
highlight%2860%28miles%2Fhour%29%29
-
You wanted an expression but not necessarily a finished value. You should be able to construct the expression for speed if that is what you wanted.

You can also find the value for d, because now you know some of the times, and you know the constant speed.

The first four hours:
60%2A4=d-507
d=60%2A4%2B507
d=240%2B507
d=747