anchor.diff:      <td><%= link_to 'Edit', edit_income_path(income) %></td>
       <td><%= link_to 'Destroy', income, method: :delete, data: { confirm: 'Are you sure?' } %></td>
     </tr>
  -<% sum += income.amount %>
   <% end %>
   </table>
   <b>Total income:</b>
  -<%= sum %>
  +<%= sum_up %>
   <br />
   
   <%= link_to 'New Income', new_income_path %>
  
positive.code:     <th></th>
      <th></th>
    </tr>
    <% sum = 0 %>
  <% @incomes.each do |income| %>
    <tr id="income">
      <td><%= income.source %></td>
  
negative.code: <h1>Listing incomes</h1>
  
  <table id="incomes">
    <tr>
      <th>Source</th>
      <th>Amount</th>
  