Answer:
The constant of variation(k) is,
Explanation:
Joint Variation states that a situation where one variable depends on two (or more) other variables, and varies directly as each of them when the others one are held constant.
i,e z varies jointly as x and y , then the equation will be of the form:
z = kxy where k is constant of variation.
Given the statement: A quantity p varies jointly with r and s.
By definition of joint variation, we have;

then;
where k is the constant of variation
divide both sides by rs, to solve for k;
Therefore, the constant of variation(k) is,