"ElseIf" and "Lookup" type functions on 1 Spreadsheet

Hello ExcelForum:

I have data in a 7 column table.
A value in G10 tells which column of that table I need to look in.
A value in J8 tells which row of that column I need.
I need to return the value of the 1st column of the table to J9.

I entered the function
=IF(G10=15,LOOKUP(J8,S2:S51,M2:M51),"n/a")
into J9, which gives me what I want only if G10=15.

How do I get it to give me the correct value if G10=3, 4, 5-6, 7-9, 10-12, OR 13-15?

My sheet is attached here Density Pay.xlsx
Thanks in advance!!

Awesome! Thanks!