Gas-condensing boilers and air-source heat pumps are considered to be substitute heating systems for residential properties. Explain how an increase in the price of gas-condensing boilers may affect the demand for air-source heat pumps over time.
119 exam-style questions on Edexcel A A Level Economics 1.2.3 Price, income and cross elasticities of demand. Each one has a worked solution and a mark scheme showing where the marks go.