can i get a explanation i keep getting 22.8 mil but its incorrect

A firm's net income is $32 million, depreciation is $2 million, its investments in fixed capital totals $12 million, its before-tax interest totals $4 million and its investment in working capital totals $5 million. The tax rate is 30%. What is its Free Cash Flow to the Firm?

a. $21.00 million b. $19.80 million c. $24.00 million d. $22.80 million