Since sum of linear pair angles is 180°
∴ 90° + x = 180°
⇒ x+180°-90° = 90°
and z+30°= 180°
⇒ z=180°-30°=150°
also y=90°+30°=120°
[Exterior angle property]
∴ x+y+x = 90°+120°+150°=360°
(b) Using angle sum property of a quadrilateral,
60°+80°+120°+n=360°
⇒ 260°+n=360°
⇒ n=360°-260°
⇒ n=100°
Since sum of linear pair angles is 180°
∴ w+100=180° …………(i)
x+120°=180° …………(ii)
y+80°=180° …………(iii)
z+60°=180° …………(iv)
Adding eq. (i), (ii), (iii) and (iv),
⇒ x + y + z + w + 100 °+ 120° + 80° + 60° = 180° + 180° + 180° + 180°
⇒ x + y + z + w +360°=720°
⇒ x + y + z + w = 720°-360°
⇒ x + y + z + w = 360°

Class 8 Maths Chapter 3 Exercise 3.1 Solution in Video