Add difference column for given column values in crystal report

Question

I have made crosstab report with Section (Fuel/Lube) and Nature (Finished/Semi-Finished) as row headers and month (September/October) as column header and value as summary field.

What I want is another column having difference for each row summary field for the given months i.e. September, October,....

Answer 1

I Found the solution.

I made a subreport for difference column only, with same parameters as in main report and

called the subreport after linking i.e. crystal report asks for linking the report parameters

on subreport addition.