FPDF中PHP的百分比计算

I am looking to make a percentage calculation on an FPDF based invoice template which contains $total (e.g 1000) and a number value $percentage (e.g. 20)

Ideally I would like this to display as discount

$pdf->Cell(100, 5, 'Discount' .$discountresult. '', 0, 'L');

How to achieve this? Some advice would be appreciated.

Like this:

$total = 1000;
$percentage = 20;

$discountResult =  $total - (($percentage / 100) * $total);

$pdf->Cell(100, 5, 'Discount' . $discountResult, 0, 'L');