km.php

<?php
$deals = [
    1 => ['forfait' => 60, 'km' => 0.12],
    2 => ['forfait' => 0, 'km' => 0.6],
];

foreach ($deals as $deal => $dealData) {
    echo 'Deal '.$deal.': forfait '.($dealData['forfait'] === 0 ? 'gratuit' : 'de '.$dealData['forfait'].'.-').' et '.
        ($dealData['km'] * 100).' cts le kilomètre.'.PHP_EOL;
}
echo PHP_EOL;

$displayData = [];
foreach (range(1, 300) as $km) {
    $bestPrice = PHP_INT_MAX;
    $bestPriceDeal = 1;

    $data = ['km' => $km];

    foreach (array_keys($deals) as $deal) {
        $price = $deals[$deal]['forfait'] + ($km * $deals[$deal]['km']);

        if ($bestPrice === $price) {
            $bestPrice = $price;
            $bestPriceDeal = null;
        } else if ($bestPrice > $price) {
            $bestPrice = $price;
            $bestPriceDeal = $deal;
        }

        $data['deals'][$deal] = number_format($price, 2);
    }

    foreach ($data['deals'] as $deal => $price) {
        $data['deals'][$deal] .= ($deal === $bestPriceDeal ? ' (best)'."\t" : "\t\t");
    }

    $displayData[] = $data;
}

$t = "\t";
$line = '+--------------------------------------------------------------+'.PHP_EOL;
$header = "|{$t}Km{$t}|{$t}Deal 1{$t}{$t}|{$t}Deal 2{$t}{$t}|".PHP_EOL;
echo $line.$header.$line;
foreach ($displayData as $displayDataItem) {
    echo "|{$t}{$displayDataItem['km']}{$t}|";
    foreach ($displayDataItem['deals'] as $deal => $price) {
        echo "{$t}${price}|";
    }
    echo PHP_EOL;
}
echo $line;