Tell me who is a factor of who and who is a multiple of who.

36 is a multiple of 9, and 9 is a factor of 36.

28 is a multiple of 4, and 4 is a factor of 28.

49 is a multiple of 7, and 7 is a factor of 49.

40 is a multiple of 5, and 5 is a factor of 40.