JAMB 2012 · UTME · Q26

The angles of a pentagon are $x$ , $2x$ , $3x$ , $4x$ and $5x$ . Find the value of $x$ .

Worked solution (try it first)

The interior angles of a pentagon add up to $(5 - 2) \times 180^\circ = 540^\circ$ .
So $x + 2x + 3x + 4x + 5x = 540$ , which is $15x = 540$ .
Divide by 15: $x = 36^\circ$ , option D.