SOLUTION: An auto tourist made a trip of 275 miles in 8 hours. Before noon he averaged 40 mph, and after noon he averaged 25 mph. At what time did he begin his trip and when did he end it?

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: An auto tourist made a trip of 275 miles in 8 hours. Before noon he averaged 40 mph, and after noon he averaged 25 mph. At what time did he begin his trip and when did he end it?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 824833: An auto tourist made a trip of 275 miles in 8 hours. Before noon he averaged 40 mph, and after noon he averaged 25 mph. At what time did he begin his trip and when did he end it?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the distance he traveled in miles before noon
+275+-+d+ = the distance he traveled in miles after noon
------------
Let +t+ = the time in hours he traveled before noon
+8+-+t+ = the time in hours he traveled after noon
---------------------------------------------
Equation before noon:
(1) +d+=+40t+
Equation after noon:
(2) +275+-+d+=+25%2A%28+8+-+t+%29+
--------------------------
By substitution:
(2) +275+-+40t+=+200+-+25t+
(2) +15t+=+75+
(2) +t+=+5+
and
+8+-+5+=+3+
His trip started at 12:00 minus 5 hrs = 3:00 AM
It ended at 12:00 plus 3 hrs = 3:00 pm