Life's A - B

So, it turns out that many things in life can be equated as A - B. You have to increase something and reduce something else at the same time to have a net positive effect. It's just not enough to look at A & B separately.

Here are some examples that come to my mind.

Savings = Income - Expense

Profit = Revenue - Cost

Personal Health related:

To loose weight = Exercise - Food

To gain weight = Food - Exercise

Economy's Health = Value of Goods & Services produced - Debt

First two are straight from the books. It seems like a pretty simple equation but we have such a hard time following it at private & public level.