Answer:
At 1:25 P.M.
Explanation:
Thomas arrived at the library at 11:45 AM and he left 1 hour 40 minutes later.
So, 1 hour 40 minutes is equivalent to (60 + 40) = 100 minutes.
Now, after 15 minutes, the time will be 12 P.M.
So, remaining (100 - 15) = 85 minutes i.e. 1 hour and 25 minutes the time will be 1:25 P.M.
Therefore, Thomas leaves the library at 1:25 P.M. (Answer)