8) You own San Antonio's top rated food truck that sells the best carne asada tacos (good A) but the burger food truck (good B) next door just started a promotional sale: The burger truck dropped/decreases their prices 22.5% This has caused the quantity demanded of tacos to decrease by 12.5%

- Find the cross elasticity of demand (for tacos with respect to the price of burgers)

- Determine whether the cross-elasticity demand for a substitute is positive or negative.

9) You recently received a 20% raise at work (change in income). Now that you're making money you shop only at Central Market H-E-B. Your grocery bill (quantity demanded) for groceries has gone up by 12%.

- Find the income elasticity of demand

- Determine whether the income elasticity of demand is positive or negative.