Answer:
C. 60º
Explanation:
A triangle is called a right triangle when one of it's angle measures 90°.
We have been given the second angle as 30°.
The angles in a triangle add up to 180°.
∴ leting the third angle to be X;
X + 30° + 90° = 180°
X + 120° = 180°
X = 180° - 120°
= 60°