In the diagram above, AB, CD and XY are straight lines intersecting at W. Find…

Explanation

a = 40^o (vertical opp. ∠s are equal) b = 60^o
a + b + c = 180^o (sum of ∠s on a str line)
40^o + 60^o + c = 180^o
C = 180^o - 100^o
C = 80^o