I need a reminder on how to do these questions, thanks

Question

Dog food A is sold in 20 kg bags and has a calorie content of 3500 kcal/kg. The bag costs $42. Dog food B is sold in 25 kg bags and has a caloric count of 3000 kcal/kg. The bag costs $50. For a dog that needs 750 kcal/day of food, which bag is cheaper? Calculate the cost per day for each food.

Answer 1

A. Good for 14/3 days, (3500 / 750)

B. Good for 4 days, (3000 / 750

 

A. $9 / day, (42 ÷ 14/3)

B. $12.50 / day, (50 ÷ 4)