Ally ran 5 miles in 36 minutes.
Ally's speed is (5 miles)/(36 minutes) = 0.13888 miles per minute.
At that speed, Ally would run 6 miles in (6 miles)/(0.13888 miles/min) = 43.2 minutes.
Ally runs faster than Sami, so Sami must take longer to run 6 miles than Ally.
The only time that is longer than 43.2 minutes is 48 minutes.