Equations of straight lines are in the form y = mx + c (m and c are numbers). m is the gradient of the line and c is the y-intercept (where the graph crosses the y-axis).
11:45 ---> 01:20
11:45 + (00:15 + 01:00 + 00:20)
= 01:20
So your answer is:
01:35 which is 1 hr, 35 mins.
72 hours I hope this helps