There are three values in the Dropdown a
1) Default blank value. (Always a "0")
2) Yes. (Depending on selction under which column)
3) No. (Always a "0")
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If "Yes" is selected under Old Navy exclusively then the answer in total should be 26,

If "Yes" is selected under Old Navy and (Ross or TJX) then the answer in total should be 26 +8,

If "Yes" is selected under Old Navy and (Ross & TJX) then the answer in total should be 26+8+8,

If "Yes" is selected under Old Navy and (Target or Walmart) then the answer in total should be 26+4+4,

If "Yes" is selected under Old Navy and (Target & Walmart) then the answer in total should be 26+8+8,

There are different probabilities depending on the selction of "Yes" and the answer in the Total should reflect and add only to that...

Hope I have been able to expalin well with the call-outs..

Thanx in anticipation..