Question

The three angles of a quadrilateral are 76°, 54° and 108°. Find the measure of the fourth angle.

Answer 1

Sum of all the four angles of a quadrilateral is 360°.

$$\begin{gathered} \mathrm{Let}\mathrm{the}\mathrm{unknown}\mathrm{angle}\mathrm{be}x°. \\ 76+54+108+x=360 \\ 238+x=360 \\ x=122 \end{gathered}$$

The fourth angle measures 122°.