Problem in joining tables in subqueries

OneLearn Course SQL
,
#1

Q.14.Write a query that counts the number of companies founded and acquired by quarter starting in Q1 2012.
Create the aggregations in two separate queries, then join them.

Q.15.Write a query that ranks investors from the combined dataset above by the total number of investments they have made.

I have done Q.14. Now in Q.15 i am confused that should i again join investments tables(there are 2 of them) ,
if YES then how to use join again in subqueries as I have already used a Full join in Q.14.

IF NO can i use acquisition table for total investments amount as it should be equal to acquisition_amount

#2

Question 15: Write a query that ranks investors from the combined dataset above by the total number of investments they have made

Here the combined dataset can be obtained by using UNION ALL for tutorial.crunchbase_investments_part1 and tutorial.crunchbase_investments_part2.

Here you need to select and group by the investor_name column. And then count the investments using COUNT(*), order by the count in descending order that was calculated. Sample subquery for combining the data is

( SELECT *
          FROM tutorial.crunchbase_investments_part1
         
         UNION ALL
        
         SELECT *
           FROM tutorial.crunchbase_investments_part2
 )
#3 
SELECT  sub.investor_name,count(sub.investor_permalink) AS number_of_investments
FROM (SELECT *
          FROM tutorial.crunchbase_investments_part1
         
         UNION ALL
        
         SELECT *
           FROM tutorial.crunchbase_investments_part2
	 ) sub

GROUP BY 1
ORDER by 2 DESC

I am doing it this way but not understanding how to connect it with answer .14