前台如何书写检测费用

<ext:GroupPanel ID="GroupPanel5" Layout="Anchor" Title="开票信息" runat="server" BoxFlex="2">
<Items>
<ext:NumberBox ID="Num101" Label="检测费用" runat="server" MinValue="0" DecimalPrecision="2" Enabled="false">
<Listeners>
　　<ext:Listener Event="change" Handler="onNum102Change" />
</Listeners>
</ext:NumberBox>

<ext:NumberBox ID="Num102" Label="费用调整" runat="server" DecimalPrecision="2" Enabled="false" >
<Listeners>
<ext:Listener Event="change" Handler="onNum102Change" />
</Listeners>
</ext:NumberBox>
<ext:NumberBox ID="Num103" Label="实际费用" runat="server" CssClass="red" Enabled="false" />

</Items>
</ext:GroupPanel>

var Num102ClientID = '<%= Num102.ClientID %>'; //库存总量
var Num101ClientID = '<%= Num101.ClientID %>'; //实际消耗量
var Num103ClientID = '<%= Num103.ClientID %>'; //实际消耗量

function onNum102Change() {
//alert("1");
F(Num103ClientID).setValue(F(Num101ClientID).getValue() + F(Num102ClientID).getValue());

}