Answer:
x = 111º
Step-by-step explanation:
In a heptagon, (A polygon with 7 sides, and therefore 7 angles), the sum of the interior angles is always 900º (just like the sum of all interior angle in a quadrilateral is always 360º). So you can add up all of the interior angles, and subtract them from 900º.
900º - (158º + 120º + 126º + 125º + 121º + 139º) = 111º
