Find CPM, ad spend or impressions when you know the other two.
Find CTR, clicks or impressions, or the total CTR of several campaigns.
Find ROAS and break-even ROAS, or the blended ROAS of several channels.
Find CLV, lifetime profit and the order that pays back what a customer cost to win.
Find CPC, or the most you can pay per click to hit a target cost per conversion.
Find your cost per acquisition and whether each sale makes or loses money after its ad cost.