How do I get a net income or net loss when all they give me is assets and liabilities and an investment and a drawings?
Assets=397,890
Liabilities= 139,538
Investments=88,467
Drawings=20,715

Not enough information given. You need beginning and ending figures to solve this type of problem.

The equation to calculate Net income for this type of problem is: Ending Owners Equity = Beginning Owners Equity + Additional Investments + Net Income (Revenues - Expenses) - Drawings

This equation can be rewritten as: Net Income = Ending Owners Equity - Beginning Owners Equity - Additional Investments + Drawings