x^2 - y^2 - 2y - 1
x^2 - (y+1)^2
Answer:
90 arrangements
Step-by-step explanation:
Since there are no repititions of letters, there are unique 10 letters in total.
THe number of arrangements would be 2 permutation 10. We need the formula for permutation. That is:

Now, n = 10 [total] and r is 2, so we have:

So, there can be 90 arrangements
You subtract 7% from 32=29.76
Then you subtract 8% from 29.76=27.379