The given problem is a COMBINATION problem because Player A and Player B paired with each other is just similar to Player B and Player A.
The formula for combination is:
[tex]\text{nCr}=\frac{n!}{r!(n-r)!}[/tex]Our n = 28 and r = 2. Let's apply this to the formula above.
[tex]\text{nCr}=\frac{28!}{2!(28-2)!}=\frac{28!}{2!26!}=\frac{28\times27}{2}=\frac{756}{2}=378[/tex]There are 378 possible different first-round matches.
