The order is for 75mg of Demerol syrup the syrup contains 50mg of Demerol per 5ml calculate dosage?

I am a pharmacist. 7.5 mL (1.5 teaspoonfuls) of 50 mg per mL Demerol syrup will contain 75 mg. It is a simply and straightforward calculation, but if it helps, you can think of 50 mg per 5 mL as being 10 mg per mL. Therefore, 7.5 mL of the syrup contains 75 mg.