Knowing angle properties

This task is about angle properties.
A sculpture has been made with a triangular base and a straight top piece.
The angles in the triangle are all different and the top piece is parallel with the base of the triangle.
 
knowing-angle-properties-diagram.png

Question

a) Which angle is the same as angle b? (Select one)

    • a

    • x 

    • c 

    • y

Question

b)  Which angle is the same as angle c? (Select one)

    • a 

    • b

    • x

    • y

c) How did you work out questions a) and b)?

Question

d) What do angles a + b + c add up to? (Select one)

    • 90º

    • 180º 

    • 270º 

    • 360º

e) How did you work out question d)?