Hi Abir,
Can you replace the line
rbv_api.updateRecord('show_rest', id, {'the_amount_payable':sunOfSal},{'rest':rest});
with the below line and try again?
rbv_api.updateRecord('show_rest', id, {'the_amount_payable':sunOfSal,'rest':rest});
Since the Rollbase do not have any API as updateRecord(string,string,object,object).
Regards,
Shiva
Did that work?