Besar sudut R adalah........

∠R + ∠Q = 180°
2x - 20 + 3x = 180
5x - 20 = 180
5x = 200
x = 40°

∠R = 2x -20
=2(40) - 20
=80 -20
=60°

2x-20+3X : 180°
5x-20: 180°
5x : 180°+20°
5x : 200°
X : 200°/5
X : 40°
sudut R: 2.40-20 : 60°