Your question is Promotions System Design. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Given a budget, design a system that recommends discount promos to maximize profit.
Asked in the ML design stage. Visible only via a commenter quoting the OP's walled post.
Address the following:
No traffic, catalog, latency, or budget figures are provided, so state reasonable assumptions before sizing the system.