# how long does it take for them to be 99 km away from each other?

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Bill and Bob cycle in opposite directions. Bill cycles at 12 km/h and Bob cycles at 13 km/h. Bill starts 2 hours before Bob does. From the time Bob begins cycling, how long does it take for them to be 99 km away from each other?

Bill and Bob cycle in opposite directions. Bill cycles at 12 km/h and Bob cycles at 13 km/h. Bill starts 2 hours before Bob does. From the time Bob begins cycling, how long does it take for them to be 99 km away from each other?

##### 1 Answer

5 hours

#### Explanation:

Bill cycles at 12 km/h and starts 2 hours before Bob does, so when Bob starts, they are already 24km fewer away from each other. This means that when Bob starts cycling, they are 75 km away from each other.

Every hour that they both cycle, they get 25km further apart (Bill gives 12km of distance at Bob gives 13km of distance). This means that it will take 3 hours for them to be the additional 75 km away.

Combined with the time Bill cycled before Bob started, it will take them 5 hours to be 99km away from each other.