octagon?

PLEASE HELP

1.What is the sum of the measures of the interior angles of a heptagon?

A. 1260∘

B. 2520∘

C. 900∘

D. 1800∘

my answer is C

5.If the sum of the interior angle measures of a polygon is 3600∘, how many sides does the polygon have?

A. 22 sides

B. 20 sides

C. 18 sides

D. 10 sides

MY ANSWER ?

3.What is the angle measure of each exterior angle of a regular octagon?

A. 45∘

B. 135∘

C. 360∘

D. 1080∘

MY ANSWER ?