The letters a, b, c, d, e, f, g, h and i are to arranged to form letter words without replacement. all nine of the letters are to be arranged to form nine letter words without replacement. how many ways can this be done if the word must contain the strings ac and bde? all nine of the letters are to be arranged to form nine letter words without replacement. how many ways can this be done where a is before b, b is before c, c is before d and d is before e? all nine of the letters are to be arranged to form nine letter words without replacement. how many ways can this be done where a is before b, b is before c, e is before f and f is before g? all nine of the letters are to be arranged to form nine letter words without replacement. how many ways can this be done if the letter a must be next to the letter b (we must have either the string ab or the string ba) and the letter c must be next to the letter d? all nine of the letters are to be arranged to form nine letter words without replacement. how many ways can this be done the letter a must not be next to the letter b (we must not have either the string ab or the string ba) and the letter c must not be next to the letter d?