PLEASE HELP! I'm having trouble answering the following problem:

Tanner furniture company concluded its FIRST year of operations in which it made sales of 800,000, ALL on installment. Collections during the year from down payments and installments totaled 300,000. Purchases for the year totaled 400,000; the cost of merchandise on hand at the end of the year was 80,000.
INSTRUCTIONS:
Using the installment-sales method, make summary entries to record:
(a) the installment sales and cash collections;
(b) the cost of installment sales;
(c) the unrealized gross profit;
(d) the realized gross profit;

We will not give you the answer. You need to submit your own work for further guidance.

However, as a guide to help you:
(1) Read your text book for entries to be made
(2) Cost of Installment sales is Purchases less Ending Inventory
(3) Unrealized gross profit is (Sales - Cost of Sales)/Sales
(4) Realized gross profit is Cash collected x Gross profit rate

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