Your question is SQL Join for Customer Subset. 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).
If you have two tables, one containing a few customer IDs and the other containing information for all customers, how do you get a table that contains only the information corresponding to the customers IDs in the first table.