Change POST values ​​on web pages? Does the riddle help?

Question

I'm a little new here, and I have a programming / coding question that maybe you could have helped me. Currently, I play this game on the network www.darker-future.nl, which is a kind of site that you got to hack / use information technology to improve the level. How would I get stuck at this level, which is obviously not enough for coding?

I got this HTML source on the page:

<form method='POST' action='**************.html'>
<input type=hidden name='40+b+c*d' value='2354'>
<input type=hidden name='a*30-c+d' value='8937'>
<input type=hidden name='a-b-20/d' value='3639'>
<input type=hidden name='a%b+c-10' value='3954'>
<input type=hidden name='a+b*c*d' value='9284'>
<input type=hidden name='a-b/c-d' value='6573'><!-- +0.5 -->
<input type=text name='a*b/c/d'><br>
<input type=submit>
</form>

I think I need to change the values ​​from hidden input fields with the correct answers or something else. My question is: how can I easily override POST values?

PS. Any tips about the possibilities that I forgot to think about at this level, please share.

Answer 1

Firefox, Firebug, HTML value. .

Answer 2

, , POST " " .

, a, b, c d 6 , ( ), .

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Answer 3

firebug Firefox. . HTML firebug, .

HTTP- .