Final answer:
The price of textbooks will increase due to the tax, but the specific increase will depend on the demand and supply conditions.
Step-by-step explanation:
When the government imposes a tax of $20 per book on all textbooks, the price of textbooks will increase. The extent to which the price increases depends on the price elasticity of demand and supply. In this case, the price elasticity of demand for textbooks is -0.3, which means that demand is inelastic. On the other hand, the elasticity of supply is 0.9, indicating that supply is relatively elastic.
Since demand is inelastic, the tax burden will mainly be borne by consumers. The price of textbooks will increase by less than $20, but the exact increase cannot be determined without knowing the initial price and quantity demanded.
Overall, the price of textbooks will increase due to the tax, but the specific increase will depend on the demand and supply conditions.