Answer:
28 g solute per 100 g of solution
Step-by-step explanation:
28% mass means that in all your solution you have 28% of your solute, you could use grames/grames, ml/ml or whatever you want to. So if you are working with a 100 grams solution, 28 grams of that solution must be solute if you want a 28% mass. So, the correct answer is 28 g solute per 100 g of solution.