Sum of angles of a triangle = 180°

Given,

∴ x + 3x + y = 180

⇒ y + 4x = 180 ------- (1)

Also, 3y – 5x = 30 ------- (2)

Multiplying eq1 by 5 and eq2 by 4 and adding them

⇒ 5y + 12y = 900 + 120

⇒ y = 60

Thus, 60 + 4x = 180

⇒ x = 30

∠A = 30° , ∠B = 90° and ∠C = 60°

Triangle is right angled at B.