Answer:
Total Stockholders' equity is $348.000
Explanation:
Stockholders are defined as the owners of stock in a company, so in this case the important thing is the total Common Stocks issued by the company, it doesn't matter if the company had good result during the year or if it pays dividends, the main point here is the quantities of shares and its value.
So, the total value of stockholders equity is equal to $348.000 which is $320.000 + 28.000.
The Retained gains belong to the company and it´s the company who decides if pays dividens or use the money to buy assets, so it doesn't belong to the stockholders until it's paid in dividends.
Once the retained gains are paid the money doesn't belong to the company anymore, it's not part of the company's equity.