Question

Find the value of x and unknown interior angle for each triangle

Answer 1

All angles added together equal to 180 degrees.
The right angle, or angle C in this case is 90 degrees.
So, angles C + B = 140
This means, angle D equals 40
So, work backwards to find x
40 = x + 20
Subtract 20 on both sides, meaning x is equal to 20

Answer 2

The value of x=20 therefore the angle measure is 40.