How is elasticity related to the revenue from a sales tax?

1. how is elasticity related to the revenue from a sales tax? illustrate with one real-world example 2. who pays a tax is not necessarily who bears the burden. explain with one real-world economics example. 3.what is a production function? why is it important to distinguish between marginal and average product? illustrate with a real-world example 4.what is the role of the firm? economists assume the goal of the firm is profit maximization, do you agree or disagree and why? explain with an example