37.375 yuan a catty. According to the query of Sohu Education Network, 1 kg is equal to 500 grams, so how much is 29.9 yuan 400 grams equal to one kilogram can be calculated: (29.9 yuan divided by 400 grams) multiplied by 500 grams is equal to 37.375 yuan per kilogram. So 29.9 yuan 400 grams equals 37.375 yuan a catty.