Buy onion jokes

1 yuan a catty, that is, green onions and green onions are one yuan a catty. When he bought it separately, the weight of green onions was 7 cents, and that of green onions was 3 cents, but the unit price changed. Green onions are less than 3 cents per catty, green onions are less than 7 cents per catty, and I bought them for 50 yuan at last.