Final answer:
The partial derivative of the demand function q with respect to price p for CI brand Cheagers, given the specific values p = 7 and ps = 12, is a calculus problem requiring the computation of the partial derivative while keeping other variables constant.
Step-by-step explanation:
The student has asked for assistance in finding the partial derivative of the demand function q = 17 (5ps - 4p)²/⁵ with respect to the price p, where ps is the average price of a substitute and p = 7, ps = 12. This type of problem lies within the realm of calculus, particularly dealing with the concept of partial derivatives. The partial derivative of a function with several variables is the derivative of that function with respect to one of those variables, while keeping the other variables constant. Applying this concept to our function allows us to understand how the demand for CI brand Cheagers changes with a change in their price while keeping the price of substitutes fixed.