In the given case Bill Stewart has contributed land valued at $10,000 and a building valued at $70,000 to form a partnership. It means the value of assets contributed by Bill Stewart is 10,000+70,000 =$80,000.
In addition to the above assets, the partnership also will pay the $50,000 mortgage payable on the building that bill contributes. It means Bill has transferred a liability to the firm.
So, Bill Stewart’s capital should be credited with 80,000-50,000 = $30,000
