SOLUTION: Hey guys, could you please help me with this problem. I'm really having trouble with it. The county's new asphalt paving machine can surface 1km of highway in 10 hours. A much olde

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Hey guys, could you please help me with this problem. I'm really having trouble with it. The county's new asphalt paving machine can surface 1km of highway in 10 hours. A much olde      Log On

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Question 25844: Hey guys, could you please help me with this problem. I'm really having trouble with it. The county's new asphalt paving machine can surface 1km of highway in 10 hours. A much older machine can surface 1km in 18 hours. How long will it take them to surface 21 km of highway if they start at opposite ends and work day and night?
Thank you again!
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
x%2F10%2Bx%2F18=21
common mulitple = 90
90%28x%2F10%29%2B90%28x%2F18%29=90%2821%2F1%29
9x+5x=1890
14x=1890
x=135
Hence, it will take them 135 hours.
Paul.