I want with formulas and with detailed explanation pls

1. John holds 10 percent interest in SS Partnership for past three years. His basis in the partnership is $200,000 which includes a $100,000 share of nonrecourse debt that is allocated to him. ITohn sells his interest in the partnership to Sally for $400,000, what would be Sally's tax basis in the partnership interest? a. $200,000 b. $300,000 $400,000 d. $500,000