How to do a partial sum of table rows in LiveCycle - Javascript

I have 4 rows (and 3 columns) in a table. The last row is the total. I need to sum only the first two rows, excluding the last one. The problem is they are all calculated values from different tables, how do I do it? I am new to Adobe LiveCycle and Javascript.

This is what I currently have:

var times = xfa.resolveNodes("Row2[*].Time"); this.rawValue = Calculate.SumRawValues(times);

I am trying something like this:

var times = xfa.resolveNodes("Row2[*].Time"); var timesFlushing = xfa.resolveNode("Row2[2].Time"); this.rawValue = Calculate.SumRawValues(times)- timesFlushing.value;

or something like this:

var times = xfa.resolveNodes("Row2[*].Time"); this.rawValue = Calculate.SumRawValues(times)- xfa.resolveNode("Row2[2].Time");

or even this:

this.rawValue = Row2.Time + xfa.resolveNode("Row2[1].Time")

Clearly I am new to this and none of these work. Help please??? Comments?