ANSWER
[tex]36[/tex]EXPLANATION
Recall, that the sum of interior angles of a regular polygon is calculated using the formula;
[tex](n-2)180[/tex]Hence, The measure of an interior angle (a) of a regular polygon of n sides is given by:
[tex]a=\frac{(n-2)\times180}{n}[/tex]Now, set this equal to 170 and solve;
[tex]170=\frac{(n-2)\times180}{n}[/tex]Multiply both sides by n;
[tex]\begin{gathered} 170n=(n-2)\times180 \\ 170n=180n-360 \end{gathered}[/tex]collect like terms;
[tex]\begin{gathered} 170n=180n-360 \\ 360=180n-170n \\ 360=10n \\ 10n=360 \\ n=\frac{360}{10} \\ =36 \end{gathered}[/tex]Therefore, the polygon has 36 sides.