The question is missing some parts. But the problem here is asking the journal entries for April 2, May 3, and June 1.
Apr 2:
Debit Accounts Receivable 1,200
Credit Sales Revenue 1,200
May 3:
Debit Cash 600
Credit Accounts Receivable 600
June 1
Debit Accounts Receivable 18
Credit Interest Revenue 18
Computation: 1200 – 600 = 600 * 0.03