Why is it that answer and how do I solve 23 and 24 and why

Clothing funits per monthy 12 20 Fred cunits per month) Figure 4.1.2 20) Refer to Figure 4.1.2. The connection of points B and D forms: overto another. C) a price-consumption curve. ne books sold then you 22) If two goods are substitutes, the cross-price elasticity of demand must be: 22) B) positive. Scenario 2,1: The demand for books is: Qd - 120 - P The supply of books is: Qs - 5P 23) Refer to Scenario 2.1. If P = $15, whist will be the result in the market? 23). 24) The demand for packs of Pokemon cards is given by the equation QD - 500,000 - 45,000P. At $5.00 per pack, what is the price elasticity of demand