tỉ 1/9
hiệu : 3abc - abc = 3000
abc là : 3000 : ( 9-1 ) = 375
=>abc*9=3000+abc
=>abc*9-abc=3000
=>abc*8=3000
=>abc=3000:8
=>abc=375
abc x 9 =3abc ==> abc x 8 + abc = 3000 + abc
abc x 8 = 3000 ==> abc = 3000 : 8
abc = 375
abc x 9 = 3abc
abc x 9 = 3000 + abc
abc x 9 - abc x 1 = 3000
abc x 8 = 3000
abc = 3000 : 8
abc = 375
=>abc*9=3000+abc
=>abc*9-abc=3000
=>abc*8=3000
=>abc=3000:8
=>abc=375
