no 19 tolong bantuannya..

3x + 10 + 4x + 30 = 180
7x + 40 = 180
7x = 180 - 40
7x = 140
x = 20

CEF
= 3x + 10
= 3.20 + 10
= 60 + 10
= 70°

GFB
= 4x + 30
= 4.20 + 30
= 80 + 30
= 110°