Calculated member in cross tab report

[NASR]

Hello,

I need help with performing calculations using crosstabs in Crystal Reports.

This Gross Margin at the bottom  is the calculated member

this is the formula that is used to  budget

GridValueAt(GetIndexOf("Command.U_Sub","Sales"), CurrentColumnIndex, CurrentSummaryIndex)-

GridValueAt(GetIndexOf("Command.U_Sub","Cost of Raw Materials"), CurrentColumnIndex, CurrentSummaryIndex)

this is the formula that is used to calculate total Actual 

GridValueAt(GetIndexOf("Command.U_Sub","Sales"), CurrentColumnIndex, CurrentSummaryIndex)-

GridValueAt(GetIndexOf("Command.U_Sub","Cost of Raw Materials"), CurrentColumnIndex, CurrentSummaryIndex)

this is the formula that is used to calculate total Variance

GridValueAt(GetIndexOf("Command.U_Sub","Sales"), CurrentColumnIndex, CurrentSummaryIndex)-

GridValueAt(GetIndexOf("Command.U_Sub","Cost of Raw Materials"), CurrentColumnIndex, CurrentSummaryIndex)

Now I want to calculate the total variance% by dividing the total variance by the total budget value.

(259,160.47)/455,926.85=(0.57).How can I do this?