Consider a retail firm with a net profit margin of 3.56%, a total asset turnover of 1.86, total assets of $45.2 million, and a book value of equity of $18.7 million.

a. What is the firm's current ROE?

b. If the firm increased its net profit margin to 4.24%, what would be its ROE?

c. If, in addition, the firm increased its revenues by 20% (maintaining this higher profit margin and without changing its assets or liabilities), what would be its ROE?