SOLUTION: a bus travel certain average speed for a distance of 75km and then travel a distance of 90km at an average speed of 10km per hour more than first speed if it takes 3 hours to compl

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Question 1065226: a bus travel certain average speed for a distance of 75km and then travel a distance of 90km at an average speed of 10km per hour more than first speed if it takes 3 hours to complete the total journey and find its first speed
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
              SPEED   TIME    DISTANCE

First Part       r      x      75

Second Part     r+10    y      90

Total                   3

x%2By=3

highlight_green%2875%2Fr%2B90%2F%28r%2B10%29=3%29

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r%5E2-45r-250=0

General solution to quadratic equation ...
r=%2845%2B55%29%2F2
highlight%28r=50%29