What is the value of y?

Answer:
40°
Step-by-step explanation:
We know that a triangle is equal to 180°
Since one angle is 50° we can figure out that the rest of the angles are equal to 130° (180° - 50°)
If we use 40° then 2·(40°) = 80°
and the second angle is 40° + 10° = 50°
if we add all the angles (80° + 50° + 50°) we get 180° which is correct.