Reset count when another button is pressed

I have a lots of articles that have 1, 2, 3 or 4 pictures. On mobile I created a carousel. All images all on the same line and I have a count that is 0. And when I press on the right button(for example) that count it will be -100 and all images will have a left: -100 and so on. The problem is that, let’s say, I press on the button from one article that count will be -100. but after I go to another article and if I press again the count is not -100 and is -200. How can I reset that count when I change the article. The code is something like:

<div class="article">
  <div class="minus">Minu</div>
  <div class="plus">Plus
  </div><div class="num">0</div>
</div>
<div class="article">
  <div class="minus">Minu2</div>
  <div class="plus">Plus2
  </div><div class="num">0</div>
</div>
<div class="article">
  <div class="minus">Minu3</div>
  <div class="plus">Plus3
  </div><div class="num">0</div>
</div>
<div class="article">
  <div class="minus">Minu4</div>
  <div class="plus">Plus4
  </div><div class="num">0</div>
</div>
<div class="article">
  <div class="minus">Minu5</div>
  <div class="plus">Plus5
  </div><div class="num">0</div>
</div>

 var c = 0;
$('.plus').on('click', function(){
    c += 100
    $(this).siblings('.num').text(c)
})```