第一次使用PHP，我无法得到回声或打印工作

I have a fairly straightforward piece of code

<div id="questdiv">
    <?php
        $a = rand() % 100;
        $b = rand() % 100;
        print "What is ";
        print (string)$a;
        print " + ";
        print (string)$b;
        print "?";
    ?>
</div>

and yet the text that appears in my div is

What is "; print (string)$a; print " + "; print (string)$b; print "?
"; ?>

What have I done wrong? I tried replacing print with echo and that did the same thing.

Your file is obviously not saved as .php file.

Probably your file is called something like this:

index.html
index.htm

change it into

xxx.php

Aswell you need a Server for your PHP, to work.

Check following website, to setup your own local server and make your PHP work: https://www.apachefriends.org/en/index.html

you should try

<div id="questdiv">
<?php
    $a = rand(0,100);
    $b = rand(0,100);
 echo "what is ".$a." + ".$b."?";
?>
</div>

And check if extension is .php (file) + if server supports PHP

Btw this is the short version of your code so try using this way ;)