Checkmate in 7 moves? In the below chess position, the chess.com computer analysis says that there is a checkmate in 7 moves for Black, but I can't find the way. Can you help me find the solution? White's last move was Rxe7, which chess.com says is a blunder, allowing for the mate in 7.
Here is a solution to your question, since you changed the position, with the lines being on a board.

   [FEN "3r2k1/p3Rp1p/6p1/8/3nbP2/P1r3P1/P6P/2B1KR2 b - - 0 1"]

    1... Rxc1+ 2. Kd2 (2. Kf2 Rc2+ 3. Ke1 Nf3+ 4. Rxf3 Bxf3 5. Re8+ Rxe8+ 6. Kf1 Ree2 7. a4 Rc1#) 2... Rc2+ 3. Ke1 (3. Kd1 Nf3+ 4. Rd7 Rxd7#) 3... Nf3+ 4. Rxf3 Bxf3 5. Re8+ Rxe8+ 6. Kf1 Bg2+ 7. Kg1 Re1#