Display the the result of a substraction in a MySQL query (1 table) I've made a table that looks like this:

stop (table name)
-cityName {PK}
-schedule {PK}
-price
-routeNo


Basicly the customer wants to know what's the cost difference between 2 different stops by giving the city name of both A and B and the routeNo (routeNo is the same for both stops)

Now I have to make a MySQL query in order to display that difference:

Say City A cost 10$ and City B cost 15$ The returned value should be 5$ (price of B - price of A)

Sorry about the rookie question but I'm lost I've tried:

SELECT (b.price - a.price) AS Returned
FROM stop
WHERE a.cityName = 'A' AND b.cityName = 'B' AND routeNo = 'x';
I'd try this :


SELECT ROUND(b.price - a.price, 2) AS Returned 
FROM stop a,(select price from stop  where cityName = 'B') as b
WHERE a.cityName = 'A' AND a.`routeNo ` = '1'; 



  OR even this :


SELECT ROUND(b.price - a.price, 2) AS Returned 
FROM stop as a join stop as b 
ON a.cityName = 'A' AND b.cityName = 'B' 
WHERE a.routeNo = 'x';



  (Updated)