Step-by-step explanation:
in a parallelogram the opposite angles must be equal.
so,
125 = y + 56
y = 125 - 56 = 69°
EC intersects 2 parallel lines : AB and DC.
therefore, the intersection angles must be the same with both lines (the angles are also the same on both sides of the lines, just left-right mirrored).
so, y is the supplementary angle to z (together they have 180°).
180 = z + y = z + 69
z = 180 - 69 = 111°
and the sum of all angles in any quadrilateral is always 360°.
so,
360 = x + y + z + 125 = x + 69 + 111 + 125 = x + 305
x = 360 - 305 = 55°
