Jack and Mack both drive 40 km from home to work each day. One day Jack said to mack, "if you drive home at your usual speed, i will average 40 kmph faster than you and arrive home in 20 minutes less time." Find mack's speed.

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- Feb 16th 2010, 10:07 PMTessarinaProblem solving with Quadratics x3
Jack and Mack both drive 40 km from home to work each day. One day Jack said to mack, "if you drive home at your usual speed, i will average 40 kmph faster than you and arrive home in 20 minutes less time." Find mack's speed.

- Feb 17th 2010, 03:15 AMHallsofIvy
- Feb 17th 2010, 10:23 AMTessarina