A - B = 1365 .........(1)
For A/B, quotient = 6
remainder = 15
We know that,
quotient x divisor + remainder = Divident
6 x B +15 = A
A = 6B+15 .........(2)
From (1) and (2),
6B + 15 - B = 1365
6B - B + 15 = 1365
5B = 1365-15
5B = 1350
B = 270