Answer:
Quadrilateral
#sides = 4
#∆ = 4-2 =2
sum= n(4-2)180° = 360°
pentagon
#sides =5
#∆ = 5-2 = 3
sum = n = (5-2)180° = 540°
Octagon
#sides = 8
#∆= 8-2 = 6
sum = n = (8 - 2)180° = 1080°
Nonagon
#sides =9
#∆ =9-2 = 7
sum = n=(9-2)180° = 1260°
Heptagon
#sides= 7
#∆= 7-2 = 5
sum = n= (7-2)180° = 900°
