Make the following journal entries in good form.

1. On January 1, 2020, Entity A sold common stock for $30,000 to investors.

2. On January 3, 2020, Entity A performed services for Entity B for $1,500 on account.

3. On January 5, 2020, Entity A performed services for Entity C for $750 and Entity C paid.

4. On January 7, 2020, Entity A purchased a new computer (office equipment) from Best Buy for $500, paying $100 down, the rest on account.