Calculating Dilutions

How many grams of 5% hydrocortisone ointment and ointment base must be combined to obtain 200 grams of 1% hydrocortisone ointment?

• 200 grams

• 100 grams

• 180 grams

• 300 grams

If you combine 30 grams of 5% lidocaine ointment with 10 grams of ointment base, what is the new percent strength?​ (a)  

• 3.75
• 1.5
• 10
• 5.5