Sorry, I can't follow your example. Please indicate which fields are running totals by using labels like {#runtotname}, which are formulas {@formula}, and which are fields {table.field}. Also, if the running total results look correct to you, and if you are interested in calculating at the group level, you can place the running totals in the group footer, and just show those results. Then we can go from there. Is the issue whether you can subtract running totals? If so, the answer is yes. Go to the formula editor and enter:
{#runningtotalA} - {#runningtotalB} //or you could subtract formula results
Of course the results will differ depending on where you place the formula, details or group, but usually you want to look at the results for a group, so it would be placed in the group footer.
If you want to create another example, please also indicate specifically what fields you want to subtract and show the result you want to get. Thanks.
-LB