Here is your third question:

A firm has current assets of $$100,$ net fixed assets of $$500,$ short$-$term debt of $$70$ and long$-$term debt of $$200.$ What is shareholders' equity. Construct a balance sheet

for this company. Is net working capital positive or negative? If so by how much? $($Hint: You may utilize Example $2\mathrm{.}1$ on page $24$ of the textbook$).$