ECB = 180 - 55 = 125
Draw a line from F to A so you have two right angles in a pentagon
Interior angles of a pentagon = (n-2) 180 = 540
then CEF = 540 - 90 -90 -120 - 125 = 115 o
First, I'll just disregard the fact that this is an AoPS question.
BCD is a straight line, so we have BCE = 180 . We draw a line CG, which is parallel to AB and EF.
AB || CG, so
\(\angle ECG = \angle BCE - \angle BCG = 125^\circ - 60^\circ = 65^\circ\)
CG and EG are parallel so
\(\angle CEF = 180^\circ - \angle ECG = \boxed{115^\circ}.\)
Since AB and EF are parallel.....drop a perpendicular from AB to EF
Then both of the angles formed by this perpendicular = 90°
And angle ECD is supplemental to angle BCE....so angle BCE = 180 - 55 = 125°
And we have an irregular pentagon......and the sum of the interior angless =540°
So angle CEF can be found as
CEF + 90 + 90 + 125 + 120 = 540
CEF + 425 = 540
CEF = 540 - 425 = 115°