We know the sum of all angles in a triangle is
and they have given both the triangles two of the angles.
*****
For the one on the right, we have
The bottom left angle of the triangle on the right is
.
*****
For the triangle on the left, we do the same process.
The bottom right angle of the triangle on the left is
.
*****
Now we can find the last angle of the smaller triangle created by the overlapping larger triangles.
Using the same method as the previous ones, we get
.
*****
A straight angle is
.