Question 1203598
How many permutations of the letters {A, B, C , D, E , F , G } are
there, such that
1 A precedes B<pre>That's the number of permutations of these 6 things AB, C, D, E, F, G
taken all 6 at a time.</pre>2 A precedes B, and C precedes D<pre>That's the number of permutations of these 5 things AB, CD, E, F, G
taken all 5 at a time.</pre>3 A precedes B, and B precedes C<pre>That's the number of permutations of these 5 things ABC, D, E, F, G
taken all 5 at a time.</pre>4 C,D,E appear together in this order<pre>
That's the number of permutations of these 5 things A, B, CDE, F, G
taken all 5 at a time.</pre>5 A,B appear together in this order, as do C,D.
<pre>That's the number of permutations of these 5 things AB, CD, E, F, G
taken all 5 at a time.

You can calculate all these numbers of permutations yourself.  They're just
factorials.

Edwin</pre>