how to add two string variables in php code example

Example 1: how to combine variables and text into a string php

<?php
$number = 8;
$txt = "the number is".$number.", ok?"; //Use a dot to combine
echo $txt;
?>

Example 2: php concatenate two variables

$string = "the color is ";
$string .= "red";

echo $string; // gives: the color is red