checkbox selection issue in data table

I am using primeface 3.5 where I have datatable with check box column.Among different columns i have a column with amount and when i check any row then i have to calculate 15% of that amount and show the result in another column .My data table is like this:

<p:dataTable id="tblExamPaymentSlip" style="width:1200px;"
        value="#{examPaymentSlipMB.paymentSlipList}"
        selection="#{examPaymentSlipMB.tempList}" 
        rowIndexVar="rowsn" var="paymentSlip" rowKey="#{paymentSlip.paymentSlipId}" >
        <p:ajax event="rowSelectCheckbox"   listener="#{examPaymentSlipMB.addAmt}" process="tblExamPaymentSlip" update="dedId" />

        <p:column>
        <f:facet name="header">
                <h:outputText value="Payment" />
        </f:facet>
        <h:outputText   value="#{paymentSlip.offPaymentMasterModel.paymentAmount}" />
        </p:column>

        <p:column selectionMode="multiple" headerText="Tax"></p:column>
        <p:column>
            <f:facet name="header">
                    <h:outputText value="Deduction" />
            </f:facet>

            <f:facet name="output">
            <p:inputText id="dedId" value="#{paymentSlip.deductionAmt}" />
            </f:facet>

            </p:column>
       </p:dataTable>

Problem is that deduction amount is set in the model class but is not displayed in data table.My managed bean code is like this.

Managed bean:

public void addAmt(SelectEvent event) {

        ExamPaymentSlipModel obj =(ExamOfficialModel)event.getObject();

        for (ExamPaymentSlipModel examPaymentSlipModel : tempList) {
            if (obj.equals(examPaymentSlipModel)) {
                examPaymentSlipModel.setDeductionAmount((15*examPaymentSlipModel.getOffPaymentMasterModel().getPaymentAmount())/100);
            }
        }
     }

How can i display the amount ? Can any one help with this.