The formula to find the measure of an interior angle is

, where

represents the number of sides in the polygon. In this problem,

would represent

.
Let's plug in the value for


Let's simplify that.

Now we know that the <span>measure of an interior angle of a regular three-sided polygon is 60</span>°.
Your answer would be B!Let me know if you have any questions regarding this problem!
Thanks!
-TetraFish
Answer:
all work is shown and pictured
x=4 y=5
if we put two pharases together
the answer is as follows pic :
x=4 y=5