For adults, the rda of the amino acid lysine is 12 mg per kg of body weight. how many grams per day should a 71.0kg adult receive?

Convert the given density in mg/kg to g/kg by the dimensional analysis. This is shown below,
                             (12 mg/kg) x (1 g/ 1000 mg) = 0.012 g/kg
Multiply this quantity with the weight of the adult given above,
                       (0.012 g/kg) x (71 kg) = 0.852 g
Thus, the adult should receive 0.852 g of lysine.