Answer:
X = [68]°
Step-by-step explanation:
We know that a triangle has 180 degrees in it from the total angle measure formula:
m = 180(n-2)
Where n equals the number of sides a shape has and m is equal to the sum of interior angle measures.
m = 180(3-2)
= 180(1)
= 180
So if we know two of the angle measures, we can add them then subtract that from the total angle measure to get x.
180-(72+40) = 68
TL;DR - Add the known angle measures and subtract them from the total angle measure to get the third missing angle.
Hope this helps :)
