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Lucia travels from point A to point B at 100km/h. Jack leaves at the same time as Lucia, traveling from point B to at 50 kilometers per hour. The distance from A to B is 100 km. How long after the to leave will they meet on the road
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Let t = "How long after they leave they will meet on the road".
Lucia will cover the distance 100*t kilometers for that time.
Jack will cover 50*t kilometers.
At the moment when they will meet each other, the sum of these partial distances will be exactly equal to the whole distance of 100 km.
Therefore, your equation is
100*t + 50*t = 100.
Solve it:
150*t = 100, ---> t = = hour = 40 minutes.
Answer. It will take 40 minutes . . .
For similar solved problems see the lesson Travel and Distance problems in this site.