Chess960 puzzles: Rook endgame

The rook endgame is the most common of all: rooks and pawns on the board. Its first law is activity — a rook behind a passed pawn beats a rook passively babysitting one. The sign of a correct plan is that your rook is attacking something, not guarding something. The typical error is locking your rook into defense: it is often better to give up a pawn and keep your rook and king active.