If the quantity demanded of pears falls by 4% when the price of apples decreases by 3%, then apples and pears are best described as:
The cross elasticity of demand is defined as the percentage change in quantity demanded divided by the percentage change in the price of a substitute or complement. If the cross elasticity of demand is positive, the goods are substitutes. In this case, the 4 % decline in quantity of pears is divided by the 3 % decline in the price of apples, which is a positive number, -4 / -3 = +1.333333.