SOLUTION: A train travels at a certain average speed for a distance of 63 km. Thereafter it travels a distance of 72 km with an average speed of 6 km/hr more than the original speed. Total t

Algebra ->  Signed-numbers -> SOLUTION: A train travels at a certain average speed for a distance of 63 km. Thereafter it travels a distance of 72 km with an average speed of 6 km/hr more than the original speed. Total t      Log On


   

Question 886566: A train travels at a certain average speed for a distance of 63 km. Thereafter it travels a distance of 72 km with an average speed of 6 km/hr more than the original speed. Total time taken to complete the journey is 3 hours. What is the original average speed of the train ?
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
r = original speed for first 63 km.

________________rate_________time_______distance
First___________r____________(___)______63
Last____________r+6_________(___)_______72
TOTAL_________________________3

Basic Rule in Uniform Rates Travel, RT=D.
Use to find T=D/R.

________________rate_________time_______distance
First___________r____________63%2Fr_______63
Last____________r+6_________72%2F%28r%2B6%29_______72
TOTAL_________________________3

Solve this equation for r:
highlight_green%2863%2Fr%2B72%2F%28r%2B6%29=3%29