Question:
If the sum of the two angles of a quadrilateral is 180°. What is the sum of the remaining two angles?
Solution:
Let $(x+y)$ be the sum of the remaining two angles.
Since, the sum of all the angles of a quadrilateral is $360^{\circ}$, we have :
$180^{\circ}+(x+y)^{\circ}=360^{\circ}$
$\Rightarrow(x+y)^{\circ}=180^{\circ}$
$\therefore$ The sum of the remaining two angles is $180^{\circ}$.