SOLUTION: Travel: Connor is driving 65 miles per hour on the highway. Ed is 15 miles behind him driving at 70 miles per hour. After how may hours will ED catch up to Connor? I learned a

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: Travel: Connor is driving 65 miles per hour on the highway. Ed is 15 miles behind him driving at 70 miles per hour. After how may hours will ED catch up to Connor? I learned a      Log On


   



Question 214012This question is from textbook california algebra 1
: Travel:
Connor is driving 65 miles per hour on the highway. Ed is 15 miles behind him driving at 70 miles per hour. After how may hours will ED catch up to Connor?
I learned about d=rt but I can't seem to get this one. I understand that it is pushing me to think, but...
This question is from textbook california algebra 1

Found 2 solutions by checkley77, josmiceli:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
d=rt
15=(70-65)t
15=5t
t=15/5
t=3 hours Connor will catch Ed.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Imagine you have a stopwatch. You start it at
the exact moment that Ed is 15 mi behind Connor.
You will stop the stopwatch at the exact moment
Ed catches Connor. That means they are both
going to be driving for the same length of time.
You also know that Ed will have to drive 15 mi more
than Connor to catch him.
----------------------------------------------
You need 2 sets of equations, one for each driver
d%5Bc%5D+=+r%5Bc%5D%2At%5Bc%5D
and
d%5Be%5D+=+r%5Be%5D%2At%5Be%5D
You already know that t%5Bc%5D+=+t%5Be%5D (call them both t)
And d%5Be%5D+=+d%5Bc%5D+%2B+15
given:
r%5Bc%5D+=+65
r%5Be%5D+=+70
Now rewrite the equations
d%5Bc%5D+=+65t
d%5Bc%5D+%2B+15+=+70t
And by substitution,
65t+%2B+15+=+70t
5t+=+15
t+=+3 hrs
Ed will catch Connor in 3 hrs
check answer:
d%5Bc%5D+=+65t
d%5Bc%5D+=+65%2A3
d%5Bc%5D+=+195 mi
and
d%5Bc%5D+%2B+15+=+70t
195+%2B+15+=+70%2A3
210+=+210
OK