(a)We know the sum of all exterior angles of any polygon is 360∘ ⇒125∘+125∘+x=360∘ ⇒250∘+x=360∘ ⇒x=110∘
(b) Sum of angles of a pentagon =(n−2)×180∘ =(5−2)×180∘ =3×180∘=540∘
By linear pairs of angles, ∠1+90∘=180∘....(i)∠2+60∘=180∘....(ii)∠3+90∘=180∘....(iii)∠4+70∘=180∘...(iv)∠5+x=180∘...(v)
Adding eq. (i), (ii), (iii), (iv), and (v), x+(∠1+∠2+∠3+∠4+∠5)+310∘=900⇒x+540∘+310∘=900∘⇒x+850∘=900∘⇒x=900∘−850∘=50∘