How to run sales quotation workflow on a line with maximum line discount? AX 2012 R2

Hii,

We have a sales quotation workflow. 

Q2: If there are 10 lines in a SQ workflow, how to run workflow on maximum discount line only. 

e.g.

Line 1   Disc 10%
Line 2   Disc 12%
Line 3   Disc 15%  (Approval should run on this line only.)

Please guide how to write condition in workflow to get the required results. [Its a header level workflow.]

Like we have more lines,  

Thanks,