Please try not to double post.

-L2 = L1 + 20*log[10(d1^2/d2^2)]

L1 = 94

d1 = 1

d2 = 1500

L2 = 30.5 (or so you say)

-L2 = 94 + 20*log[10(1/1500^2)] = -13.04365

Check to make sure the numbers are correct. Check also to make sure you are looking at the correct answer (in the back of the book, I assume).