How do I write an adjusting entry for common stock using this data: I have 200 shares of common stock costing $30,000. I sale 100 shares of common stock for the price of $18,000 and I have a market value of these shares at $148 per share. Thanks

This isn't an adjusting entry.

I'm a bit confused over the way you've presented the information. Just reading it quickly, I assumed the company was issuing new shares of stock to investors. But then when I re-read it, I realized you're saying you have 200 shares and give a cost. Do you mean that you own these shares in a company and you are now selling part of them? If that is the case, you need to know your cost basis, and what you originally paid for the shares may not be the correct number to use, IF you had any dividends re-invested.

If no dividends were re-invested, and if you bought them all at the same time, it's just the difference of what you paid versus what they were sold for.

But... I still have to wonder if this is not a company issuing new shares and you're just stating it in a way that is not making this clear. So it would help if you could be way more specific so we could figure out what exactly is the situation here.