Could you please you a formula to help to understand this kind of question?

Which direction should I think about first?

Thank you so much.

Error in current Year Current-year income Ending retained earnings balance, current year Income of next year Ending retained earnings balance, next year 1. Understate ending inventory OVERSTATE UNDERSTATE OVERSTATE OVERSTATE 2. Purchase and receive goods in current period, but record purchase in next period; goods are included in inventory. OVERSTATE UNDERSTATE OVERSTATE OVERSTATE 3. Goods purchased FOB shipping point were in transit at year-end and not included in inventory; purchase was recorded. OVERSTATE UNDERSTATE OVERSTATE OVERSTATE 4. Goods shipped to a customer FOB destination were in transit at year-end and were included in inventory. The sale was not recorded. UNDERSTATE OVERSTATE UNDERSTATE UNDERSTATE