16. (8 points) The inverse demand curve for product X is given by:

PX= 25 - 0.005Q + 0.15PY,

where PXrepresents price in dollars per unit, Q represents rate of sales in pounds per week, and PYrepresents selling price of another product Y in dollars per unit. The inverse supply curve of product X is given by: PX= 5 + 0.004Q.

a. (5 points) Determine the equilibrium price and sales of X when PY= $10.

b. (3 points) Explain whether X and Y are substitutes or complements and why.