(a) Right angled
By the angle sum property of a triangle,
∠A + ∠B + ∠C = 180º
\(\Rightarrow\)x + y + y + 20° = 180° \(\Rightarrow\) x + 2y = 160 .............(i)
Given, 4x – y = 10 .................(ii)
Multiplying (ii) by 2, we get
8x – 2y = 20 ...........…(iii)
Adding eqn (i) and (iii),
9x = 180 \(\Rightarrow\) x = 20
\(\therefore\) From (i), 2y = 160 – 20 = 140 \(\Rightarrow\) y = 70
\(\Rightarrow\) ∠A = 20º , ∠B = 70º , ∠C = 90º
\(\therefore\) The triangle is right angled.