Welcome to your interview.
The question is on your right: Budget Shift and Lead Volume. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
If we shift 20% of our budget from channel A to channel B, how does that affect the overall lead volume for DeltaX?