You need to work out the other angles first, before working out the values of; a, b and c. ∠x = 180 - 139 [∠'s on a straight line] thus, ∠x = 41° ∠y = ∠x [corresponding angles] ∴ ∠y = 41°
∠h = 180 - (41 + 77 + 36) [∠'s on a straight line add to 180°] ∠h = 26°