How much is a catty of onions?

The onion seller said 1 yuan 1 kg, which means 100 kg, and it costs 100 yuan.

The onion buyer asked if the onion was sold separately from the onion.

The onion seller said that what he sold was 7 hairs and 3 hairs and green.

All the onion buyers bought it.

Weigh 50 kg of green onions and 50 kg of green onions.

The final calculation is that 50*7 equals 35 yuan.

50*3 equals 15 yuan.

35+ 15 equals 50 yuan.

The onion buyer gave it to the onion seller, leaving 50 yuan.

But the onion seller is confused.

Why do onions cost 100 yuan?

And why do you buy onions for 50 yuan?

What do you say this is?