Q) Write a query to return Territory and corresponding Sales Growth (compare growth between periods Q4-2019 vs Q3-2019)

Q) Write a query to return Territory and corresponding Sales Growth (compare growth between periods Q4-2019 vs Q3-2019).

Tables given-
Cust_Sales: -Cust_id,product_sku,order_date,order_value,order_id,month
Cust_Territory: cust_id,territory_id,customer_city,customer_pincode

Use tables FCT_CUSTOMER_SALES (which has sales for each Customer) and MAP_CUSTOMER_TERRITORY (which provides Territory-to-Customer mapping) for this question.

Output format-
TERRITORY_ID | SALES_GROWTH

My solution-
Select ((q2.claims - q1.claims)/q1.claims * 100) AS SALES_GROWTH , c.territory_id

From

(select sum(s.order_value) from FCT_CUSTOMER_SALES s inner join MAP_CUSTOMER_TERRITORY c on s.customer_id=c.customer_id where s.order_datetime between 1/07/2019 and 30/09/2019 group by c.territory_id) as q1.claims,

(select sum(s.order_value) from FCT_CUSTOMER_SALES s inner join MAP_CUSTOMER_TERRITORY c on s.customer_id=c.customer_id where s.order_datetime between 1/10/2019 and 31/12/2019 group by c.territory_id) as q2.claims

Group by c.territory_id

My solution is showing up as incorrect I would request anyone who can help me out with the solution and let me know where my mistake is

You need to expose the territory id in your two derived tables and join them on that column.
What you have there should give an error as there is no table aliased c.

The questions doesn't say what should happen if there are no sales for a territory in one of the periods so it's not well formed.