title: Subtract value of column based on another column
body: <p>I have a big dataframe (the following is an example)</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th style="text-align: left;">country</th>
  <th style="text-align: right;">value</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td style="text-align: left;">portugal</td>
  <td style="text-align: right;">86</td>
  </tr>
  <tr>
  <td style="text-align: left;">germany</td>
  <td style="text-align: right;">20</td>
  </tr>
  <tr>
  <td style="text-align: left;">belgium</td>
  <td style="text-align: right;">21</td>
  </tr>
  <tr>
  <td style="text-align: left;">Uk</td>
  <td style="text-align: right;">81</td>
  </tr>
  <tr>
  <td style="text-align: left;">portugal</td>
  <td style="text-align: right;">77</td>
  </tr>
  <tr>
  <td style="text-align: left;">UK</td>
  <td style="text-align: right;">87</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>I want to subtract values by 60 whenever the country is portugal or UK, the dataframe should look like (Python)</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th style="text-align: left;">country</th>
  <th style="text-align: right;">value</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td style="text-align: left;">portugal</td>
  <td style="text-align: right;">26</td>
  </tr>
  <tr>
  <td style="text-align: left;">germany</td>
  <td style="text-align: right;">20</td>
  </tr>
  <tr>
  <td style="text-align: left;">belgium</td>
  <td style="text-align: right;">21</td>
  </tr>
  <tr>
  <td style="text-align: left;">Uk</td>
  <td style="text-align: right;">21</td>
  </tr>
  <tr>
  <td style="text-align: left;">portugal</td>
  <td style="text-align: right;">17</td>
  </tr>
  <tr>
  <td style="text-align: left;">UK</td>
  <td style="text-align: right;">27</td>
  </tr>
  </tbody>
  </table>
  </div>