What is the measure of an interior angle of a regular polygon iwth 15 sides

To find the measure of an interior angle of any regular polygon, we use the formula:

180 * (n-2)  / n, 

where n is the number of sides in the regular polygon.

Therefore, if there are 15 sides in the regular polygon, your answer would be 

180 * (15-2) / 15, 

or when simplified,

180 * 13 / 15

2340 / 15

156 degrees.

Thus, the measure of an interior angle of a regular polygon with 15 sides is 156 degrees.