Here BD is perpendicular bisector
So

Apply Pythagorean theorem





44 [minutes] * 8 [times as many as April] = 352 [minutes in April]
Ok, so we know that RST is equal to 6x+12
And RST is also equal to 78 + 3x-12
so we set them equal to each other
6x + 12 = 3x - 12 + 78
And simplify
3x = 54
x = 18
Finally, we solve for the angle with 18 for x
6(18) + 12
108 + 12
120
Hope this helps