Question 1016005
.
Each exterior angle of a polygon with 20 sides
measures (360/20)=18 degrees. The sum of exterior
angles of all polygons is 360 degrees. 
. 
Interior angle of other polygon = 18 + 42 = 60 degrees
.
(n-2)/n(180)=60
(n-2)(180)=60n
180n-360=60n
120n-360=0
120n=360
n=3
.
ANSWER: A is correct, n=3