To calculate a lion's mass when height and weight are known, it's important to clarify that if weight is already provided, mass does not need to be calculated. The relationship between weight and mass is defined by the formula weight = mass × gravity. Therefore, if weight is given, mass can be derived directly by rearranging the formula. The discussion emphasizes the need for clarity in the question posed regarding the calculation. Understanding the distinction between mass and weight is crucial for accurate calculations.