The measure of an interior angle is 170.
\Sum of the measures of interior angles is (170)n.
\The sum of the measures of interior angles of a polyon is .
(Interior angle sum theorem)
(Substitute
)
(Distributive property)
(Subtract 170n from each side)
(Subtract:
)
(Add 360 to each side)
(Divide each side by 10)
The number of side in the polygon is 36.