Answer:
50
Explanation:
All three angles of a triangle will add up to 180. Since one angle is known, 90, the right angle, and another is known, 40, we can solve for the missing angle.
90 + 40 + x = 180
Add like terms.
130 + x = 180
Subtract 130 from both sides.
x = 50
The missing angle is 50.