Subquerys: profits

Hi guys, I need help to build a Query that gives me two columns: the date and the profit. The profit would be the “total_sales” - “total_chargeback”.

(1) approved_at and chargeback_at are dates.

I’m trying this way, but to no avail.

SELECT str_to_date(concat(date_format(`ad_moip`.`approved_at`, '%Y-%m'), '-01'), '%Y-%m-%d') AS 'Mouth_Year', SUM(total_sales - total_chargeback) AS profit
            (SELECT SUM(R.value), R.approved_at
            FROM ad_moip AS R
                WHERE approved_at IS NOT NULL 
                AND chargeback_at IS NULL
                GROUP BY R.approved_at) AS total_sales,
             (SELECT SUM(C.value), C.chargeback_at
            FROM ad_moip AS C 
                WHERE chargeback_at IS NOT NULL
                GROUP BY C.chargeback_at) AS total_chargeback   
     ORDER BY Mouth_Year ASC 
     GROUP BY Mouth_Year

All data is in the same table