If $$ y $$ varies jointly with $$ x $$ and $$ z $$ , and $$ ...

Question Analysis
This problem assesses the ability to find the constant of variation in a joint variation problem.

Key Concept Explanation
In joint variation, is directly proportional to the product of and . The relationship is given by , where is the constant of variation.

Step-by-step Solution
1. Identify the given values: , , and
2. Substitute these values into the formula