Given:
Inventory:                    $820
Fixed Assets:              $3,200
Accounts receivable: $1,210
Accounts payable:     $890
Cash:                           $360
The amount of net working capital is
Cash and cash equivalents ($360)
+ Receivables ($1,210)
+ Inventory ($820)
+ Marketable investments ($3,200)
- Accounts payable ($890)
= $4,700
Answer: $4,700