please help me my econ homework

What does the price elasticity of demand indicate (3 points)? How is the perfectly inelastic demand curve illustrated (3 points). Give an example of a good which has perfectly inelastic demand (2 points) and write down what the elasticity of perfectly inelastic demand is equal to (2 points). What does the income elasticity of demand indicate (3 points)? What is the expected sign for income elasticity of demand for an inferior good (2 point)? Explain (3 points).