Knightattack: your answer is not correct... there is no way white will do those moves.
I mean black will not win the game in that position unless white makes a mistake very unlikely for white to make mistakes.
1... Rb8xRb1 2 Rf1xRb1, let's see the position now,
[FEN "1r3rk1/5p2/2pp1Qp1/7q/N1P1P1b1/3P2Pp/P1P4P/1R3RK1 b - - 0 0"]1... Rxb1 2. Rxb1
White is 2 pawn up on black. Although black has the h6 pawn threating mate in any moment black can get its queen in 2nd file. For that matter black tries to sacrifice his bishop to block queen on getting to defensive positions. 2... Bg4-f5 3 exBf5 will never be a move white will do. This will just work if white plays that greedy move. There is no way a proggram or good player will do that move.
The main point in chess problems is to there be a positive answer. In these game black will just draw at most. after 2... Bg4-f5 white will do 3 Kf2 or 3 Qf6-d4 and not 3 e4xBf5. Now if Q cannot get to 2nd file position and retreating bishop is only plausible move. Thus there is no good answer since black does not win the game nor have any gain at all.