Question

Solve the polygon for x

Answer 1

• Octagon has sum of angles 1080°

$\\ \rm\Rrightarrow 5(10x+15)+2(14x)+6x-3=1080$

$\\ \rm\Rrightarrow 50x+75+28x+6x-3=1080$

$\\ \rm\Rrightarrow 84x+72=1080$

$\\ \rm\Rrightarrow 84x=1008$

$\\ \rm\Rrightarrow x=1008/84$

$\\ \rm\Rrightarrow x= 12$