<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Hello World 4</title>
    </head>
    <body>
        <?php
            $children = 0;
            $married = false;
            $income = 0;
            if (isset($_GET["children"]) AND isset($_GET["income"])) {
                $children = (int)$_GET["children"];
                if (isset($_GET["married"]))
                    $married = (bool)$_GET["married"];
                else
                    $married = false;
                $income = (float)$_GET["income"];
            }
        ?>
        <form>
            <label for="children">Number of children: </label>
            <input id="children" type="number" name="children" min="0" value="<?= $children ?>" required> <br />
            <label for="married">Married: </label>
            <input id="married" type="checkbox" name="married" <?= $married ? "checked" : "" ?>> <br />
            <label for="income">Income: </label>
            <input id="income" type="number" name="income" min="0" step="any" value="<?= $income ?>" required> <br />
            <input type="submit" value="Send">
        </form>
        <?php
            if ($married)
                $n = 2+$children/2;
            else
                $n = 1+$children/2;

            $q = $income/$n;

            $t = 0;
            if ($q >= 0 AND $q <= 9963)
                $t =  $income*0 - 0*$n;
            elseif ($q >= 9964 AND $q <= 27518)
                $t = $income*0.14 - 1394.96*$n;
            elseif ($q >= 27519 AND $q <= 73778)
                $t = $income*0.3 - 5798*$n;
            elseif ($q >= 73779 AND $q <= 156243)
                $t = $income*0.41 - 13913.69*$n;
            elseif ($q >= 156244)
                $t = $income*0.45 - 20163.45*$n;

            $t = round($t);

            ?>
        <p>Your taxes is <?= $t ?></p>
    </body>
</html>