Article 36 of the Standards for Consolidated Financial Statements stipulates that if a parent company sells assets (downstream transactions) to its subsidiaries, it shall fully offset the unrealized gains and losses of internal transactions against the net profits attributable to the owners of the parent company. When a subsidiary sells assets to the parent company (counter-current transaction), the unrealized internal transaction shall be offset between the net profit attributable to the owner of the parent company and the profits and losses of minority shareholders according to the distribution ratio of the parent company to the subsidiary company.
The sale of patents by Company A to Company B is an internal downstream transaction, and the unrealized internal gains and losses of the transaction are not considered when calculating minority shareholders' rights and interests. The total comprehensive income attributable to minority shareholders is (300+100) × 20% = 800,000 yuan.