What is the net operating working capital

Question

Question: A company has the following balance sheet. What is its net operating working capital?

Cash:                             $ 10
Accounts payable:           $ 20
Short-term investments:     20
Accruals:                           30
Accounts receivable            30
Notes payable:                   20
Inventory:                         40
Current liabilities:               70
Current assets:                 100
Long-term debt:                  30
Net fixed assets:                 80
Common equity:                 10
Retained earnings:              70
Total assets:                   $180
Total liability & equity:      $180