Review the following transactions and prepare any necessary journal entries for Northstar Corp.

a$.$ On January $1,$ Northstar Corp. receives an advance cash payment of $$17,100$ from a client for six months of legal services starting January $1.$

b$.$ On May $31,$ Northstar Corp. recognizes legal services provided since January $1.$

Enter the transaction letter as the description when entering the transactions in the journal. Dates must be entered in the format dd$/$mmm $($i$.$e$.,$ January $15$ would be $\frac{15}{J}an).$