<?php
$capacities = array(25,150,5000);
foreach ($capacities as $c) {
echo sprintf("Capacity of %s will be allowed to overdraw by %s.\n", $c, max($c*0.10,15));
}
Capacity of 25 will be allowed to overdraw by 15.
Capacity of 150 will be allowed to overdraw by 15.
Capacity of 5000 will be allowed to overdraw by 500.