Question 837564: A truck traveled the first 80 miles of a trip at one speed and the last 105 miles at an average speed of 5 miles per hour less. The entire trip took 5 hours. What was the average speed for the first part of the trip?
Answer by josgarithmetic(39620)   (Show Source):
You can put this solution on YOUR website! Here will be shown help to start, but not the whole solution.
Key idea is R*T=D, R for rate, T for time, D for distance.
First 80 miles at the speed, r.
Last 105 miles at the speed r-5.
_______________speed_________time_________distance
First___________r____________(____)________80
Last___________r-5___________(____)________105
TOTAL________________________5
You need to fill the information for the two time quantities. You know that the equation , r*t=80, so you can solve this for t, and that gives the expression for the First time. You understand what to do for the "Last" time?
Can you continue and finish this?
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