In △ABC and △ADE we have,
∠ ADE = ∠ ABC [corresponding angles]
x = 40°
∠AED = ∠ACB (corresponding angles)
y = 30°
We know that the sum of all the three angles of a triangle is equal to 180°
x + y + z = 180° (Angles of △ADE)
Which means: 40° + 30° + z = 180°
z = 180° – 70°
z = 110°
Therefore, we can conclude that the three angles of the given triangle are 40°, 30° and 110°
