A man went to buy onions and asked how much they cost a catty. The onion seller said 1 yuan 1 kg, which means 100 kg. I want to buy 100 yuan. The onion buyer asked again: Onions are divided into green and white. It's very simple because scallion is not 70 cents per catty, but 70 cents per 0.7 catty. The same is true of green onions. In fact, the price of a kilo of onion and onion is exactly the same as that of a single onion, so the formula should be 50 * (0.7/0.7)+50 * (0.3/0.3) =100. Thank you!