Here are the answers to the online chess puzzles numbers 17-19. I hope you found the solutions to all of them!

Chess Puzzle #17. The answer is d8/Q is checkmate. Obviously R-c8 is not mate as the king escapes on f7.

Chess Puzzle #18. The answer is Rxd8.  The black king is forced to capture the rook on d8. Then R-e8 is checkmate.

Chess Puzzle #19. The answer is Q-a8 check. Black is forced to play Kxa8. White then plays Rxa5 double check. Black is forced to play K-b8. White then checkmates black with R-a8.

Congratulations if you got them all!