Step-by-step explanation:
For 4.
4b + 2b + 3b = 180°< Sum of angles of triangle >
9b = 180°
b = 180° / 9
b = 20°
4b = 4* 20° = 80°
2b = 2* 20° = 40°
3b = 3 * 20° = 60°
For 5.
x = 64° + 45° <Exterior angle of a triangle is equal to the sum of two opposite interior angles>
x = 109°
Hope it helps :)
