好簡單的求多邊形邊數問題！！！！！！

let x degree be ab exterior angle
(180 - x) - x = 120
x = 30

360 / n = x = 30
Thus, n = 12

if an exterior angle of a regular n-sided polygon is less than its interior angle by 120度，find the value of n?
360/n>180(n-2)/n
360>180n-360
720>180n
6>n
THE VALUE OF n can be 3,4 or 5.