The anwser to your question is 1 and 5/7
Its 0 because the slope would be one if it was a positive line and itd go up and across one unitl and it is undefined if it is parallel to the y axis
If we know that 30% of the time is used after 9 minutes we can write this mathematically as:

By solving for x we can determine the total time allowed to play games and so:

The total time allowed to play games is 30 minutes. Since 9 minutes have lapsed 30-9=21 minutes left to play.