Anna received an invoice for $$6,000$ that had payment terms of $4/15$ n$/30.$ She made a partial payment of $$2,400$ during the discount period.

a$.$ Calculate the amount credited.

$$0\mathrm{.}00$

Round to the nearest cent

b$.$ Calculate the balance on the invoice after the partial payment was made.

$$0\mathrm{.}00$