x+20=30+40
x+20=70
x=70-20
x=50
x + 20 = 30 + 40
x + 20 = 70
x = 70 - 20
x = 50
x + 20 = 30 + 40
=> x + 20 = 70
=> x = 70 - 20
=> x = 50
x + 20 = 30 + 40
x + 20 = 70
x = 70 - 20
x = 50
kl : x = 50
x + 20 = 30 + 40
x + 20 = 70
x = 70 - 20
x = 50
k nha