3 yuan 300 ml of double-skin milk is a loss. The materials of double-skin milk include: milk, sugar, starch, egg white and a little dried fruit. The cost of 300 ml of milk alone is barely enough in 3 yuan. Coupled with other raw materials, processing costs, labor costs and other expenses, 300 ml of double-skin milk will be sold to around 10 yuan. So 3 yuan's 300 ml double skin milk is definitely a loss.