Natural gas produced by fracking is a substitute for some goods, i.e., the demand for these other goods falls when the price of natural gas falls. Nevertheless, natural gas is also a complement for other goods—their demands rise when the price of natural gas falls. Identify at least two goods that are substitutes for natural gas and two that are complements. Considering both producers and consumers of those goods, analyze how they are either made better off or worse off as a result of the spread of fracking.