SQL Query Solutions:

Task 4:

SELECT
Customers.First_Name, Customers.Last_Name, Cars.Model
from Sales
Join Customers on Sales.Customer_ID=Customers.Customer_ID 
Join Cars on Sales.Car_ID=Cars.Car_ID and Cars.Make='Mercedes-Benz';


Task 5:

SELECT Sales_Agents.Agent_ID, SUM(Sales.MSRP) as Total_Sales
from Sales_Agents 
join Sales on
Sales.Agent_ID=Sales_Agents.Agent_ID
Group By Sales_Agents.Agent_ID;