I got this .aspx page with no access to the source code.(apparently it was lost)

anyways. I have this form with a datagrid that access values from a database.

<TD align="left" width="293"><asp:dropdownlist id="DropDownList16" runat="server" AutoPostBack="True"></asp:dropdownlist></TD>
<TD align="middle" width="127">$<asp:label id="Label32" runat="server">0</asp:label></TD>

If you look at the code above, asp:dropdownlist is a string, but I'm not sure if asp:label is a numeric. Since I don't have the source code, how can I change the numeric value that gets to the asp:label within the aspx page.
lets say i get a number 20, and I want to add 15 to it, how can this be done.

any help would be appreciated
thank you