(a)[2]
In a pentagon, four of the angles are $2x^\circ$ and the remaining angle is $x^\circ$. Calculate the value of $x$.
(b)[2]
$ABCD$ and $EBCF$ form sections of two identical regular $n$-sided polygons. The polygons are joined along edge $BC$. Angle $DCF = 30^\circ$. Calculate the value of $n$.