Explanation:
remember, the sum of all angles in a triangle is always 180°.
and the sum of all angles around a single point on one side of a line is also 180° (because that line can be seen as diameter of a circle with that given point being the center of the circle - and a half-circle is always 180°).
so,
the inner angle at B is
180 = 130 + B
B = 50°
and then for the whole triangle
50 + 4x + 2x + 3 = 180
6x + 53 = 180
6x = 127
x = 127/6 = 21.16666666...
the angle BCD (= the internal angle at C) =
2x + 3 = 2×21.16666666... + 3 = 45.33333333... ≈
≈ 45.3°