Find the value of x and m

:calculate the sum of the interior angles of a 13-sided polygon.

What two advantages do the coastal countries of west africa have over the sahel countriesfertile soil and mineral resources temperatures and terrain human resources and natural resources weather patterns and location

Which outcome is not caused by gravitational forcea. gas and dust come together to form a planet b. planets orbit a star c. two atoms come together to form a molecule d. stars cluster to form a galaxy