Hello can someone walk me through the steps for solving this?

DISCUSSION PROMPT QUESTION 1 (REQUIRED FOR EVERYONE): Christine recently earned a promotion at work, raising her income by 40%. As a result, she now attends twice as many concerts as before. What is Christine's income elasticity of demand for concerts? Explain what this tells us about the concerts Christine attends. A. -0.40 B. 0.40 C. 1.00 D. 2.50