How should black play to save this endgame? Recently I've played a game (with blacks) which ended with this position (White to move) :  

[fen "3rk3/p1R2ppp/2p5/8/P1K5/8/1P3PPP/8 w - - 0 1"]


It's clear that White player can't protect his pawns in the second row, but the problem here is with the a file, should black protect his pawns in the a file, which will quite restrict his possibilities ?
Otherwise, Is it possible to just abandon this pawn, and go for white pawns in the 2nd raw ?
But the problem here is surely with the white pawn in a4 which is pretty advanced compared to black pawns.  

How should black play in order to save his game ( a draw at least ?!)
This endgame is lost for black, but the best plan here is for black to enter 2nd rank and try to gain some pawns and throw some checks. White's plan on the other side is just to take a7 pawn and advance his a4 pawn till promotion

Good luck trying to SAVE that one