I think a far more intuitive system is use negative numbers with a symmetrical accounting equation:
Assets - Liabilities = Income - Expense
- Do I have more or less assets?
- Do I owe more or less liabilities?
- Did I make more of less profits?
- Did I make more or less losses?
You can then use the accounting equation to check your reasoning. I go more into it here: https://news.ycombinator.com/item?id=40021375