Sama caranya yaa thx :)

garis lurus = 180 derajat

180 = ( 5x - 40 ) + ( 2x )
180 = 7x - 40
7x = 180 - 40
7x = 140
x = 140 : 7
x = 20

sudut abc =
= 5x - 40
= 5 . 20 - 40
= 100 - 40
= 60 derajat

maaf kalau salah, hehehe