x + 1000 - 200 + 900 = 9000
x = 9000 - 900 + 200 - 1000
x = 7300 ủng hộ mk nhaThảo
x + 1000 - 200 + 900 = 9000
x + 1000 - 200 = 9000 - 900
x + 1000 - 200 = 8100
x + 1000 = 8100 + 200
x + 1000 = 8300
x = 8300 - 1000
x = 7300
x+1000-200+900=9000
x+1700 =9000
x=9000-1700
x=7300