please show me the step-by-step calculations for the following drug dosage calculations. Thanks much

please show me the step-by-step calculations for the following drug dosage calculations. Thanks much.

11. A client who has a gastrostomy feeding tube is receiving 3/4 strength Ensure 240 ml every 6 hours. Full strength Ensure is available in a 240 ml can. The nurse should use how many ml of Ensure to prepare the feeding? (Enter numeric value only. If needed, round to the nearest whole number.)   answer is 240 ml, please show me step-by-step calculations .

15. A child with a urinary tract infection is receiving Cephalexin (Keflex) 100 mg suspension PO QUID. Keflex oral suspension is labeled “125 mg in 5 ml “. How many ml should the practical nurse administer? (Enter numeric value only. If rounding is required, round to the nearest tenth.) answer is 4 ml, please show me step-by-step calculations .

20. A child who weighs 55 pounds receives a prescription for atovaquone with proguanil

(Malarone Pediatric) 125 mg/50 mg PO daily. A drug reference states that children 11 to

20 kg should receive 1 pediatric tablet daily; 21 to 30 kg should receive 2 pediatric tablets

daily; 31 to 40 kg should receive 3 pediatric tablets daily; and greater than 40 kg should

receive 1 adult tablet daily with food. The drug is available as atovaquone 62.5

mg/proguanil 25 mg pediatric tablets. How many tablets should the nurse administer?  answer is 2 tablets, please show me step-by-step calculations .