Unsupported operand types: int * string

 public function transaksi_selesai_aksi()
    {
        $id                            = $this->input->post('id_rental');
        $tanggal_pengembalian          = $this->input->post('tanggal_pengembalian');
        $status_rental                 = $this->input->post('status_rental');
        $status_pengembalian           = $this->input->post('status_pengembalian');
        $tanggal_kembali               = $this->input->post('tanggal_kembali');
        $denda                          = $this->input->post('denda');

        $x                              = strtotime($tanggal_pengembalian);
        $y                              = strtotime($tanggal_kembali);
        $jumlah                         = abs(($x - $y) /(60 * 60 *24)); #hari
        $jumlah                         = $jumlah*$denda;



        $data = array(
            'tanggal_pengembalian'     => $tanggal_pengembalian,            'status_rental'            => $status_rental,            'status_pengembalian'      => $status_pengembalian,
            'total_denda'              => $total_denda,         );

controller transaksi_selesai

<div class="class main-content">
    <section class="section">
        <div class="section-header">
            <h1>DATA TRANSAKSI</h1>
        </div>
        <?php echo $this->session->flashdata('pesan') ?>
        <div class="table-responsive">
        <table class="table table-bordered table-striped">

            <tr>
                <th>No</th>
                <th>Customer</th>
                <th>Mobil</th>
                <th>Tgl. Rental</th>
                <th>Tgl. Kembali</th>
                <th>Harga/ Hari</th>
                <th>Denda/ Hari</th>
                <th>Total Denda</th>
                <th>Tgl. Dikembalikan</th>
                <th>Status Pengembalian</th>
                <th>Status Rental</th>
                <th>Status Pembayaran</th>
                <th>Action</th>
            </tr>
                <?php $no=1;
                foreach($transaksi as $tr): ?>
                    <tr>
                        <td><?php echo $no++ ?></td>
                        <td><?php echo $tr->nama ?></td>
                        <td><?php echo $tr->merk ?></td>
                        <td><?php echo date('d/m/Y', strtotime( $tr->tanggal_rental)) ?></td>
                        <td><?php echo date('d/m/Y', strtotime( $tr->tanggal_kembali))  ?></td>
                        <td>Rp.<?php echo number_format($tr->harga,0,',','.') ?></td>
                        <td>Rp.<?php echo number_format($tr->denda,0,',','.') ?></td>
                        <td>Rp.<?php echo $tr->total_denda ?></td>
                        <td>
                            <?php
                                if($tr->tanggal_pengembalian == "0000-00-00") {
                                    echo "-";
                                }else{
                                    echo date('d/m/Y', strtotime($tr->tanggal_pengembalian));
                                }
                            ?>
                        </td>
                        <td>
                            <?php echo $tr->status_pengembalian ?>
                        </td>
                        <td>
                            <?php
                                echo $tr->status_rental
                            ?>
                        </td>

                        <td>
                            <center>
                                <?php
                                if(empty($tr->bukti_pembayaran)) { ?>
                                <button class="btn btn-danger"><i class="fas fa-times-circle"></i></button>
                                <?php }else{ ?>
                                    <a href="<?php echo base_url('admin/transaksi/pembayaran/'.$tr->id_rental) ?>"><i class="fas fa-check-circle"></i></a>
                                    <?php } ?>
                            </center>
                        </td>

                        <td>
                            <?php
                                if($tr->status== "1"){
                                    echo "-";
                                }else{?>
                                        <div class="row">
                                            <a class= "btn btn-sm btn-success mr-2" href="<?php echo base_url('admin/transaksi/transaksi_selesai/'.$tr->id_rental) ?>"><i class='fas fa-check'></i></a>

                                            <a onclick="return confirm('yakin batal')" class= "btn btn-sm btn-danger" href="<?php echo base_url('admin/transaksi/batal_transaksi/'.$tr->id_rental) ?>"><i class='fas fa-times'></i></a>
                                        </div>
                                <?php  } ?>

                        </td>
                    </tr>
                <?php endforeach; ?>
        </table>
        </div>
    </section>
</div>

view_data_transaksi

CREATE TABLE `transaksi` (
  `id_rental` int(11) NOT NULL,
  `id_customer` int(11) NOT NULL,
  `id_mobil` int(11) NOT NULL,
  `tanggal_rental` date NOT NULL,
  `tanggal_kembali` date NOT NULL,
  `harga` varchar(120) NOT NULL,
  `denda` varchar(120) NOT NULL,
  `total_denda` varchar(120) NOT NULL,
  `tanggal_pengembalian` date NOT NULL,
  `status_pengembalian` varchar(50) NOT NULL,
  `status_rental` varchar(50) NOT NULL,
  `bukti_pembayaran` varchar(120) NOT NULL,
  `status_pembayaran` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

db_transaksi

selamat siang, barang kali ada yang tahu cara mengatasi kasus sepeti ini, udh cari kemana mana tapi belum ketemu hehe, mohon bantuan nya, maklum masih noob hehehe

problem.PNG