Answer :
Notice that 7:00 PM falls between 6:39 PM and 7:18 PM.
Add the differences between 6:39PM and 7:00PM and from 7:00PM to 7:18PM.
There are 21 minutes between 6:39PM and 7:00PM, and there are 18 mintues from 7:00PM to 7:18PM.
[tex]21+18=39[/tex]Therefore, there are 39 minutes between 6:39PM and 7:18PM.
The game took her 39 minutes.