SQL - Problem PL/SQL Help me!!

Construct queries (using PL SQL statements) that when executed give answers to the following questions:

1. what is the top 10 best selling dishes in the last month, show the name and amounts paid per dish.

2. For point 1 what would you propose in the model to include the prices of the dishes?

3. What is the average number of customers that visited the restaurant in the last 6 months and which were the busiest tables.

4. What do you propose to consult the data of a client taking into account: 1. If the client is new, make the record in the clients table. 2. If the customer has already been created, show the history of his consumption in the last three months.