Chart Question: Breaking down a calculated field into 2 columns to show respective amounts

Hi all,

I have a question about charts. I have 3 fields in the custom form: 'Opex amount', 'MBD amount' and then 'Total amount'. The 'Total amount' field is a calculated field which sums 'Opex amount' and 'MBD amount'. Is there a way to have a chart that breaks down the 'Total amount' into 2 columns -> 'Opex amount' and 'MBD amount'?? I haven't been able to do so. Ex: Opex -> 30, MBD ->70 = Total 100. I am trying to show a column with 30 on one side and another with 70 on the other side.

Thanks!