Question

What is the value of x? Enter your answer in the box.

Answer 1

It's a heptagon.

The formula of the sum of internal angles in the polygon:

$S=(n-2)\cdot180^o$

Therefore

$120^o+158^o+126^o+125^o+121^o+139^o+x^o=(7-2)\cdot180^o\\\\789^o+x^o=900^o\ \ \ \ |-789^o\\\\x^o=111^o$