If price of a commodity rises by 40% and accordingly its demand fallss by 80% what is `P_(e_(D)`

If price of a commodity rises from ₹ 8 to ₹10 per unit and its demand falls by 50% what is e_(D) ?

If the price of a commodity is decreased by 40% and its consumption is increased by 20% , then what will be the increase or decrease in the expenditure of the commodity?

When price of a commodity falls by 80 % , the quantity demanded of it increases by 100 %. Find out its price elasticity of demand.