In reviewing the books of SRB International Incorporated, an auditor discovered certain errors were made during 2021 and 2022. No errors had been corrected and none of the accounts had yet been closed for 2022. a. Beginning inventory, January 1, 2021, was understated by $4,000. b. Merchandise with a cost of $1,000 was sold for $1,500 on December 30, 2021, but was not recorded until 2022. The merchandise was not included in the 2021 inventory. SRB International uses a periodic inventory system. c. A 2-year insurance policy was purchased on July 31, 2021, for $3,000. The entire amount was debited to insurance expense and no adjusting entries have been made. d. A 6-month note receivable of $5,000 was held by SRB International beginning November 1, 2021. Payment of the 8% note and interest was received upon maturity. No adjusting entry was made on December 31, 2021. Required Prepare journal entries for December 31, 2022, that correct each of the independent errors in parts (a) through (d). Income taxes are to be ignored. Show your supporting calculations.

Please help; I know these are the solutions but I need help explaining why.

a. No journal entry is necessary as error self corrected in 2021. restatement is necessary. b. Sales revenue.. . 1,500 Retained earnings 1,500 c. Prepaid insurance ($3,000 x 7/24). 875 Insurance expense ($3,000 ~ 12/24)... 1,500 Retained earnings ($3,000 * 19/24). 2,375 d. Interest revenue ($5,000