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 always 180° (because that line is like a diameter of any circle with that point as center, and half a circle is 180°).
3)
the third inner angle of the triangle is
180 = 63 + 51 + angle = 114 + angle
angle = 66°.
x = 180 - 66 = 114°
4)
the third inner angle of the triangle is
180 = 86 + 45 + angle = 131 + angle
angle = 49°
x + 30 = 180 - 49 = 131°
x = 101