如何使用php在excel表中读取公式栏

I have some doubt for this Excel Reading. I Using Maths formula bar in my excel but I don't know how to read this value.

Please Help me This part

If your are using PHPExcel, you can get answer from PHPExcel docs. For example if if is simple sum fromula, it seem like

$objPHPExcel->getActiveSheet()
    ->setCellValue(
        'B10',
        '=SUM(A10:B9)'
    );