Your answer is gonna be the second one!
If you mean
you can first substitute 
to get
and so
On the graph, it shows that the shortest meeting has lasted for 1/4 of an hour. An hour has 60 mins, you know it the shortest will be 15 minutes.
If its for any other number that you do not know, you can list as a proportion:
1/4 = x/60 (1 and x are on the top of the fractions)
Cross multiply: 1 * 60 = 60
Then divide by the number on the opposite corner of x: 60/4
x = 15
No the angle of each piece should be 60 degrees, if the three pieces were to be 25 each that would only add to 75
Their average value is the even integer between the middle two, 184/4 = 46.
Your integers are 43, 45, 47, 49.
