The demand curve of a commodity is expressed as ` D_(x)=40-5P` . If slope of the demand curve is given to be (-2) , calculate price elasticity of demand for the commodity when demand is 20 units.

Explanation

`D_(x)=40-5P`: putting the value of demand (i.e 20 units) we get 20 = 40 -5P , i.e p=₹ 4.
Elasticity of Demand `(E_(d))=(DeltaQ)/(DetlaP)xx P/Q OR 1/("Slope of Demand curve")xx P/Q`
Elasticity of Demand `(E_(d))=1/(-2)xx4/20 =(-)0.10`