Answer :

AL2006
Assuming that the 30 is term #1 ..... The 'n'th term of the series is. T(n) = 33 - 3n or 3 (11 - n).
Find the multiplication by subtracting the second term from the first term
27 - 30 = -3, so the multiplication table is -3x.
Now find the deviation of the first term in this sequence from the first term of the original -3x table
30 - -3 = 33
So you're adding 33 to the terms to get the sequence given
Final equation is:
-3n + 33