If the price of a substitute for a good increases, what is the likely effect on the equilibrium price and quantity of the original good, assuming demand is elastic?

When the price of a substitute good increases, consumers tend to buy more of the original good because it becomes relatively cheaper. This increased demand for the original good leads to a rise in both its equilibrium price and quantity. For example, if the price of butter goes up, people might buy more margarine instead, driving up the demand for margarine. Since demand is elastic, even a small change in price can result in a significant change in the quantity demanded. Overall, the original good benefits from the increase in demand, leading to higher prices and sales.