title: Write a query join sum groupby in laravel
body: <p><br>
  Please help me write query.<br>
  I have 2 table: "projects" and "debts"<br>
  "debts" table have<br></p>
  
  <pre><code>id | project_id | currency_list | total
  1  | 1          | 1             | 1000
  2  | 1          | 2             | 500
  3  | 2          | 1             | 1000
  4  | 2          | 2             | 500
  ...
  </code></pre>
  
  <p>I need write query to take 1000 rows from projects and SUM all "total" with group by "currency_list"</p>
  
  <p>Thanks a lot :)</p>