\[Price{\text{ }}Elasticity{\text{ }}of{\text{ }}Demand = \frac{{{\text{ }}% \Delta {\text{ }}Quantity{\text{ }}Demanded}}{{% \Delta {\text{ }}Price}}{\text{ }}\]
\[Price{\text{ }}Elasticity{\text{ }}of{\text{ }}Demand = {\text{ }}\frac{{\Delta {\text{ }}Quantity{\text{ }}Demanded/Quantity}}{{\Delta {\text{ }}Price/Price}}\]
\[Cross{\text{ }}Price{\text{ }}Elasticity = {\text{ }}\frac{{% \Delta {\text{ }}Quantity{\text{ }}Demanded}}{{% \Delta {\text{ }}Price{\text{ }}Of{\text{ }}Related{\text{ }}Goods}}\]
\[Income{\text{ }}Elasticity = \frac{{% \Delta {\text{ }}Qmantity{\text{ }}Demanded}}{{% \Delta {\text{ }}in{\text{ }}Income}}\]