Question:
The angles of a quadrilateral are 110°, 72°, 55° and x°. Find the value of x.
Solution:
The sum of anlges of a quadilateral is $360^{\circ}$.
So, we get $110^{\circ}+72^{\circ}+55^{\circ}+x=360^{\circ}$
$\Rightarrow 237^{\circ}+x=360^{\circ}$
$\Rightarrow x=360^{\circ}-237^{\circ}$
$\therefore x=123^{\circ}$