Question

(360°/n) - (360°/n+2)= 30° without quadratic equation

Answer 1

360/n -360/n+2 = 30
30[12/n-12/n+2] =30
12n+24-12n=n^2 +2n
n^2+2n-24=0
n^2+6n-4n-24=0
n(n+6) -4(n+6)=0
n=4,-6