Answer:
39
Explanation:
The short answer is 39.
Every triangle has 180 degrees. There are no exceptions to this rule.
Since a triangle has 3 angles, all three together must add up to 180o
A right angle = 90 degrees always.
You are given 51 degrees as your second angle
The third one is x
x + 51 + 90 = 180 Total of three angles must be 180
x + 141 = 180 The left has been added to give 141
x = 180 - 141 Subtract 141 from both sides
x = 39 The third angle = 39