In a toy manufacturing company, the manufacturer needs to pay rent (p) each month and monthly electricity (q). To produce each toy, the company incurs costs for plastic (r) and for cloth (s). The variables p, q, r, and s are positive constants. Given the cost model as cost = fixed cost + variable cost

a. Define the cost model with the given unknowns.

b. How does plastic and cloth affect the cost model?

c. Will the variable plastic influence the cloth variable?