How Do You Find Percent Change In Quantity Demanded?

How Do You Find Percent Change In Quantity Demanded? Find the price elasticity of demand. So, the percentage change in quantity demanded is -40 (the change, or fall in demand) divided by 80 (the original amount demanded) multiplied by 100. -40 divided by 80 is -0.5. Multiply this by 100 and you get -50%. What