1 dollar a catty

This is 100 pounds

To finish $100

The onion buyer asked again

Do you sell the white onion separately from the green onion

The onion seller said

Sell

White onion is 70 cents

Green onion is 30 cents

All the onion buyers bought them

Weighed 50 catties of white onions

50 catties of green onions

Finally counted 50*7 for white onions equals 35 yuan

50*3 for green onions equals 15 yuan

35+15 equals 50 yuan

Buyers gave 50 yuan to sellers of green onions and went on their way

While sellers of green onions were puzzled

Why did the man who bought the onions buy them for 50 dollars when he was obviously going to sell them for 100 dollars

Why did the man who bought the onions buy them for 50 dollars?

Why do you think that is?