I need to post to General Ledger the following:

21 Billed customers for cleaning offices $670

29 Received $300 from the cusomters billed on the 21

How do I post these?

21 Billed customers for cleaning offices $670

dr. Accounts Receivable 670
Cr. Service Income 670
To record accounts receivable on service rendered

29 Received $300 from the cusomters billed on the 21
dr. cash 300
Cr. Accounts Receivable 300
To record partial payments received