70° 50° (4r + 20)° 'ada gambar di alas, nilai x=... pakai Cara

→ Pelurus 4x + 20 :
= 180 - (4x + 20)
= 180 - 4x - 20
= 160 - 4x

160 - 4x + 70 + 50 = 180
-4x = 180 - 160 - 70 - 50
-4x = 20 - 120
-4x = -100
x = 100/4
x = 25