tolong jwb ya pake cara kalo ada

Sudut + Pelurus = 180°
(Sudut = 2/7 Pelurus)
2/7P + P = 180°
2/7P + 7/7P = 180°
9/7P = 180°
P = 180 x 7/9
P = 140°

Maka , sudut =2/7P = 2/7 x 140 = 40°