Hello Raj
Let ABCD be the quadrilateral.
Given Sum of two angles is two right angles
So, ∠ A + ∠ B = 180
Now, we know that
Sum of angles of quadrilateral is 180
So, ∠ A + ∠ B +∠ C + ∠ D = 360
(∠ A + ∠ B) +∠ C + ∠ D = 360
180 +∠ C + ∠ D = 360
∠ C + ∠ D = 360 - 180
∠ C + ∠ D = 180
So, sum of other two angles is 180
Written on Nov. 6, 2017, 8:10 p.m.