I'll give you a question, please answer with step-by-step reasoning process.
John buys 30 ducks for $10 each. They weigh 4 pounds and he sells them for $5 per pound. How much profit did he make?

300
He bought the ducks for 30 * 10 = $300.

He sold each duck for 4 * 5 = $20.

So he sold all the ducks for 30 * 20 = $600.

So he made a profit of 600 - 300 = $300.

.

The answer: 300