In triangle PQR Angle P + Angle Q + Angle R = 180° x+3x+y=180 4x+y=180 →(1) Given, 3y−5x=30 → (2) From (1) and (2) we get x=30 and y=60 The three angles P, Q and R of the triangle are respectively 30° , 90° and 60° Hence the triangle is a right-angled triangle.