Assets Liabilities Capital Stock Retained Earnings
Case A $23,000 $11,000 A $ 4,500
Case B 17,500 B $ 4,500 3,600
Case C C 14,000 11,000 27,000
Case D 45,000 29,000 18,000 D

The equation is absolutely in your textbook, because it's the backbone of many concepts in accounting:
Assets = Liabilities + Stock + Retained Earnings

Plug in the numbers given and solve for the missing ones. (And this thing loses columns when you post so no way to tell where those are. If you go into the "Go Advanced" button you will get a preview of your post.