A client's profits are declining. How do you structure the case?

How to answer

Profit = Revenue - Cost, so I'd first isolate which side is driving the decline. On revenue, I'd break it into Price x Quantity, with Quantity = market size x our share, segmenting by product, region, or customer. On costs, I'd split fixed vs. variable and find what's grown. I'd also test whether the cause is internal (our operations) or external (market-wide), since that determines whether it's a problem we created or one we're absorbing. Then I'd lead with a hypothesis on the likely driver and start there.

Key idea: Listing revenue and cost ideas as a flat brainstorm instead of a clean equation tree; also forgetting to first ask whether the decline is industry-wide vs. company-specific.