P Co, the parent company of a group, owns shares in three other companies. P Co's holdings are: Q Shares giving control of 60% of the voting rights in Q Co R Shares giving control of 20% of the voting rights in R Co. P Co also has the right to appoint or remove all the directors of R Co S Shares giving control of 10% of the voting rights in S Co, plus 90% of the non-voting preference shares Which of these companies are subsidiaries of P Co?