How do i do the journal entry?

I'm doing a business project. My question is Pane sells window panes to customers. Some customers paid in cash, other purchased their goods on account. Pane uses the perpetual method to track their inventory.

- cash sales .              15,000,000

-sales on account .    30,000,000

-COGS                         20,,000,000 

How do I do the journal Entry?