The own-price elasticity of demand is calculated by wA demand curve is described as perfectly elastic if a. the same quantity is purchased regardless of price b. the same price is charged regardless of quantity sold c. neither price nor quantity demanded ever change d. only price can changehich of the following? a. change in price divided by the change in quantity demanded b. percentage change in price divided by the percentage change in quantity demanded c. percentage change in quantity demanded divided by the change in price d. percentage change in quantity demanded divided by the percentage change in price