Answer:
From the above attachment we can conclude that the sum of the angle 'b' and 40° is 90° (right angle)
[tex]b + 40 ^\circ = 90 {}^{ \circ} \\ b = 90 {}^{ \circ} - 40 {}^{ \circ} \\ \boxed{ b = 50 {}^{ \circ} }[/tex]
- b = 50° is the right answer.
