Leratong Enterprises has accounts payable of R300, inventory of R250, cash of R50, non-current assets of R500, accounts receivable of R200, and long-term debt of R400. What is the value of the net working capital to total assets ratio? A 0.20 B 0.33 C 0.40 D 0.50

Please provide reasoning for why 0.20 is the answer. Thank you :)