A van travels at $$80\text{km}$$ per hour to another city. $$3$$ hours later, a car travels at $$120\text{km}$$ per hour towards the same city from the same place. In how many hours can the car catch up with the van?     Below is Mason\textquotesingle s answer.  $120-80=40$  $120\div40 = 3$  The car can catch up with the van in $3$ hours.     Is Mason\textquotesingle s answer correct? If not, what is the correct answer? 
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