This problem relies on the knowledge of the sum of the angles inside a triangle.
Consider the diagram below. It shows the same triangle cloned three times and joined together. Notice that the three angles A, B, and C form a straight line at the center. It is a given fact that a straight line measures 180°. Therefore, all angles inside a triangle must add up to 180°.
In the problem, we already know the two angles. We just need to subtract these angles to 180° to get the third angle.
ANSWER: The third angle needs to be 84°.
Consider the diagram below. It shows the same triangle cloned three times and joined together. Notice that the three angles A, B, and C form a straight line at the center. It is a given fact that a straight line measures 180°. Therefore, all angles inside a triangle must add up to 180°.
In the problem, we already know the two angles. We just need to subtract these angles to 180° to get the third angle.
ANSWER: The third angle needs to be 84°.