Help! This so confusing I want to quit

Calculate the amount of sodium iodide powder needed to prepare 30 mL of 4% sodium iodide solution, using water as the solvent.

Calculate the amount of potassium chloride powder needed to prepare 250 mL of 10% potassium chloride solution, using water as the solvent.

Calculate the amount of pure ethanol needed to prepare 200 mL of 60% ethanol solution, using water as the solvent.

Calculate the amount of sodium chloride powder needed to prepare 1 liter of 0.45% sodium chloride solution, using water as the solvent.

Calculate the amount of dextrose powder needed to prepare 600 mL of 5% dextrose solution, using water as the solvent.

Calculate the amount of salicylic acid powder needed to prepare 150 g of 10% salicylic acid ointment.

Calculate the amount of progesterone needed to prepare 240 g of 2% progesterone vaginal suppositories.

Calculate the amount of cream base needed to prepare 50 g of 1.5% lidocaine cream.

Calculate the amount of zinc oxide powder needed to prepare 20 g of 15% zinc oxide ointment.

Calculate the amount of Vaseline ® needed to prepare 1.5 oz. of 15% salicylic acid ointment.

Calculate the amount of 2% lidocaine stock solution needed to prepare 40 mL of 1.5% lidocaine solution, using water as a diluent.

Calculate the amount of 40 mg per mL furosemide solution needed to prepare 30 mL of 25 mg per mL furosemide solution, using furosemide solution strengths of 40 mg per mL and 20 mg per mL.

Calculate the amount of 50% dextrose solution needed to prepare 300 mL of 7.5% dextrose solution, using water as a diluent.

Calculate the amount of ointment base needed to prepare 50 g of 1.5% hydrocortisone ointment from 2% hydrocortisone ointment.

Calculate the amount of 5% dextrose solution needed to prepare 200 mL of 10% dextrose solution from 5% and 50% stock solutions.