China Petroleum & Chemical Corporation (Sinopec) provides two sets of financial statements in its annual report. One set of financial statements is prepared in accordance with Chinese (PRC) Accounting Rules and Regulations, and the other is prepared in accordance with IFRS. The company also provides a reconciliation of IFRS net income and net assets to U.S. GAAP. Sinopec reported the following amounts under three different sets of accounting rules in its 2006 annual report:

Required:
a. Determine the percentage difference in net profit attributable to shareholders and average total equity attributable to equity shareholders for 2006 under the three different sets of accounting rules.
b. Calculate return on average total equity (Profit attributable to shareholders/ Average total equity) for 2006 under the three different sets of accounting rules.
c. Determine the percentage difference in return on average total equity under the three sets of rules.
d. Which of the three measures of return on average total equity is most useful in assessing Sinopec's profitability?