Answer:
D) 40
Explanation:
To solve the question you can use the knowledge that every triangle has a total of 180 degrees. Two of the angles are known one is 50 and the other is 90. We know one is 90 because of the square around the angle. Then, you can set up an algebraic equation to solve. We know that 50+90+x=180, so solve for x for the final answer of 40.