Get the value of a testbox

Hello, I built a report which returns some calculated fields and I would like to know if it's possible to use the returned values in another field.

Exemple:
textbox10 = Fields!MyColumn.Value
textbox11 = Fields!MyOtherColumn.Value

I would like to know if there is a way to do something like this:
textbox12 = textbox10 + textbox11

Has anyone any idea? Thanks in advance for your help

Use the ReportItems collection i.e.

Code Snippet

textbox12 = ReportItems!textbox10.Value + ReportItems!textbox11.Value