Alabama NR Prorated exemption calculation

I had a small income ( $158) from a DST property located in Alabama (AL). I am an AL non resident

In a different post, I asked if I have to file a return for AL, the answer was:

 

You are required to file an Alabama (AL) return if as a nonresident your income is over the allowable prorated exemption (full year resident amounts are $3,000 for married filing jointly and $1,500 for single).  AL Instructions

 

I am still confused about how to calculate the prorated exemption?  

Let's say the total income is  $100,000  and the Alabama income is  $10

Would my prorated calculation be  100,000 /10 = 10,000    or  10/100,000 = 0.0001 ?

 

2. What number I need to use? Is it the total income or the taxable income?  In my return, those are 2 different numbers: the taxable income is the total income minus deductions.