1. The problem statement, all variables and given/known data The demand function for a certain product is given by pq=4000, where p is the price charged per item and q is the quantity which can be sold at that price. If the product currently sells for $3.50 per item, what would be the rate of change of quantity over time if the rate of change of price over time is $0.50? 2. Relevant equations pq=4000 3. The attempt at a solution Honestly, the getting started part is what is tripping me up. The equation looks simple enough but TOO simple. It's throwing me off! I know I need to find the derivative, so I'm thinking (3.50)q=4000, but I'm so unsure!!