how many mL of a 20% w/v solution of NaCl are needed to make up 200 mL of a 5%…

how many mL of a 20% w/v solution of NaCl are needed to make up 200 mL of a 5%…

how many mL of a 20% w/v solution of NaCl are needed to make up 200 mL of a 5% solution