The mass of salt in 200 ml of a solution with a mass fraction of 0.18 and a density of 1.2 g / ml is

m (salt) = V (solution) p (solution) W (salt) = 200ml * 1.2g ml * 0.18 = 43.2g

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.