Oil companies have to work harder for those profits Re: “Oil companies raise prices to maintain profits,” From Readers, April 4

Andrew Liptak needs a quick lesson in economics. There’s a difference between profit — which is simply revenue minus expenses — and profit margin, which is the real barometer of business success. The raw profit number only tells you the difference between your income and your expenses. A $1,000 profit is one thing for a $100 lemonade stand, but quite another for a million-dollar electronics store.