Molarity help? how to make a 3% solution?

All the three solutes are SOLIDS--.Keep all the solids in a desicator over the porcelain slieve in the upper chamber,the lower chamber containing a dehydrant for about 30 minutes.Then weigh exactly 15 grammes of each solid --put each solid in a seperate measuring Cylinder (500 ml capacity) and dissolve in a small amount of distilled water and make up the volume in each cylinder to 500ml.Acetyl salicylic acid may require about 2 drops of dilute NaOH to convert the acid to sodium salt which will dissolve easily.They will be 3% solution of each solute.