SELECT r.*
     , coalesce(SUM(cr_subq.field_a) - SUM(cr_subq.field_b), 0) AS field_result
FROM table_r r
LEFT JOIN (
    SELECT
           c_id
         , r_id
         , c.field_c * 0.05 AS field_a
         , c.field_c * 0.05 * r.percent / 100 AS field_b
    FROM table_cr cr
    JOIN table_r r on cr.r_id = r.id
    JOIN table_c c on cr.c_id = c.id
    WHERE status IN ('status1', 'status2')
) cr_subq on r.id = cr_subq.r_id
GROUP BY r.id
ORDER BY field_result DESC, r.id DESC
;