Viết sai 1 dấu, làm lại :
Ta có:
abc x 126 = 15abc
=> (a.100+b.10+c) .126 = 15(a.100+b.10+c)
=> (a.100+b.10+c) .126 = 15000+ a.100 + b.10 + c
=> (a.100+b.10+c).126 - (a.100 + b.10 + c) = 15000
=> (a.100+b.10+c).(126 - 1) = 15000
=> (a.100+b.10+c). 125 = 15000
=> abc=15000 : 125
=> abc=120
Vậy abc là 120
Ta có:
abc x 126 = 15abc
(a.100+b.10+c) .126 = 15(a.100+b.10+c)
(a.100+b.10+c) .126 = 15000+ a.100 + b.10 + c
(a.100+b.10+c).126 - (a.100 + b.10 + c) = 15000
=(a.100+b.10+c).(126 - 1) = 15000
(a.100+b.10+c). 125 = 15000
abc=15000 : 125
abc=120
Vậy abc là 120