For any n-sided (regular) polygon the interior angles are given by [tex]180-\frac{360}{n}[/tex]
So for each shape listed:
Hexagon:
[tex]180-\frac{360}{n}[/tex]
[tex]180-\frac{360}{6}=120[/tex]
Decagon:
[tex]180-\frac{360}{n}[/tex]
[tex]180-\frac{360}{10}=144[/tex]
Pentagon:
[tex]180-\frac{360}{n}[/tex]
[tex]180-\frac{360}{5}=108[/tex]
Octagon:
[tex]180-\frac{360}{n}[/tex]
[tex]180-\frac{360}{8}=135[/tex]
Nonagon:
[tex]180-\frac{360}{n}[/tex]
[tex]180-\frac{360}{9}=140[/tex]
Heptagon:
[tex]180-\frac{360}{n}[/tex]
[tex]180-\frac{360}{7}=128\frac{4}{7}[/tex]
