Based on the corporate valuation model, Wang Inc.$\text{'}$s total corporate value is $$850$ million. Its balance sheet shows $$60$ million notes payable, $$120$ million of long$-$term debt, $$40$ million of common stock $($par plus paid$-$in$-$capital$),$ and $$160$ million of retained earnings. What is the best estimate for the firm's value of equity $($in millions$)?$

a$.$ $$790$ million

b$.$ $$670$ million

c$.$ $$730$ million

d$.$ $$690$ million

e$.$ $$710$ million