<tr>
  <%= form_for [object.event, object], remote: true do |f| %>
    <td><%= f.text_field :name, class: 'form-control' %></td>
    <td><%= f.number_field :capacity, class: 'form-control', placeholder: 100 %></td>
    <td><%= f.text_field :price, class: 'form-control', placeholder: "0.00" %></td>
    <td><%= form_check_box f, :public %></td>
    <td><div class="checkbox"><%= f.check_box :has_comment %></div></td>
    <td><div class="checkbox"><%= f.check_box :hidden %></div></td>
    <td><%= f.button button_name, class: 'btn btn-sm btn-primary' %></td>
    <%= javascript_tag do %>
      var id = "#edit_<%=dom_id(f.object) %>";
      var inputs = $(id).parent().find('input');
      $(id).parent().find('button').on('click', function() {
        $(id).append(inputs.clone());
        $(id).append('<input type="hidden" name="_method" value="put">');
        $(id).submit();
      });
    <% end %>
  <% end %>
</tr>

<tr>
  <%= form_for [object.event, object], remote: true do |f| %>
    <td><%= f.text_field :name, class: 'form-control' %></td>
    <td><%= f.number_field :capacity, class: 'form-control', placeholder: 0 %></td>
    <td><%= f.text_field :price, class: 'form-control', placeholder: "0.00" %></td>
    <td><%= form_check_box f, :public %></td>
    <td><div class="checkbox"><%= f.check_box :has_comment %></div></td>
    <td><div class="checkbox"><%= f.check_box :hidden %></div></td>
    <td><%= f.button button_name, class: 'btn btn-sm btn-primary' %></td>
    <%= javascript_tag do %>
      var id = "#edit_<%=dom_id(f.object) %>";
      var inputs = $(id).parent().find('input');
      $(id).parent().find('button').on('click', function() {
        $(id).append(inputs.clone());
        $(id).append('<input type="hidden" name="_method" value="put">');
        $(id).submit();
      });
    <% end %>
  <% end %>
</tr>

Change capacity placeholder from 100 to 0
Change capacity placeholder from 100 to 0

As some people got confused that y default only 100 tickets are allowed.
