5ab + ab = 678
(5+1) x ab = 678
6 x ab = 678
ab = 678 : 6
ab= 113
\(5ab+ab=678\)
\(=>6ab=678\)
\(=>ab=678:6=113\)
Vậy \(ab=113\)
5ab + ab = 678
=> (500 + ab) + ab = 678
=> 500 + 2 x ab = 678
=> 2 x ab = 678 - 500 = 178
=> ab = 178 : 2 = 89
5ab+ab=678
500+ab+ab=678
2. ab=678-500
2.ab=178
ab=178:2
ab=89
5ab + ab = 678
500 + ab + ab = 678
ab x 2 = 678 - 500
ab = 178 : 2
ab = 89
