.net - Make Crystal Report Of Profit And Loss Statement?

i want to make crystal report of profit and loss statement i have a column of "vr_type" and there are 4 types in it "sale invoice", purchase invoice" now i want that put a 4 formula s where i select that "sum (vr_detail.debit) where vr_detail.vr_type} sale invoice it make Sum of al these types so kindly tell me what formula i should use to get the result in simply i want sum of sale,sum of purchase,sum of expense?