you have to find out first whether the polygon is regular or not.If it is,then the sum of the exterior angles of any polygon which is 360 will be divided by 36(the exterior angle. The answer which is 10 determines the number of sides. from there, use the formula, S(Sum of the interior angles)=180(n-2).So,
S=180(n-2)
S=180(10-2)
S=180(8)
S=1440
This is nw the sum of the interior angles of the polygon