Given that,

l ‖ m

Let, l ‖ m and transversal cuts them and

∠1 = 70^o

∠3 = 20^o

∠4 = 30^o

∠1 + ∠2 = 180^o (Interior angle)

∠2 = 110^o (i)

∠2 = ∠5 (Vertically opposite angle)

∠5 = 110^o (ii)

∠5 + ∠3 + ∠4 = 180^o (Sum of angles of a triangle is 180^o)

110^o + x + 30^o = 180^o

x = 40^o