Who are the customers?
select cust_name from customer
Which of them have mortgage loans?
select t1.cust_name from customer as t1 join loan as t2 on t1.cust_id = t2.cust_id where loan_type = 'Mortgages'
And which also have auto loans?
select t1.cust_name from customer as t1 join loan as t2 on t1.cust_id = t2.cust_id where loan_type = 'Mortgages' intersect select t1.cust_name from customer as t1 join loan as t2 on t1.cust_id = t2.cust_id where loan_type = 'Auto'