Question:
Three angles of a quadrilateral are equal. Fourth angle is of measure 150°. What is the measure of equal angles.
Solution:
Let $x$ be the measure of the equal angle $s$ of the quadrilateral.
Since, the sum of all the angles of a quadrilateral is $360^{\circ}$, we have:
$x^{\circ}+x^{\circ}+x^{\circ}+150^{\circ}=360^{\circ}$
$\Rightarrow 3 x^{\circ}=360^{\circ}-150^{\circ}$
$\Rightarrow x^{\circ}=210^{\circ}$
$\therefore$ The measure of each angle is $70^{\circ}$