In parallelogram RISK,
∠RIS = ∠=120° [Angles of linear pair]
Opposite angles of a ||ᵍᵐ are equal]
∠m+120°=180° [Linear pair]
⇒ ∠m+180°-120°=60°
and ∠ECI = ∠L=70°
[Corresponding angles]
⇒ m+n+∠ECI=180°
[Angle sum property of a triangle]
⇒60°+n+70°=180°
⇒ 130°+n=180°
⇒ n=180°-130°=50°
also x = n = 50°
[Vertically opposite angles]

Class 8 Maths Chapter 3 Exercise 3.3 Solution in Video

for more answers vist to:
https://www.tiwariacademy.com/ncert-solutions/class-8/maths/chapter-3/