Following query will get you result for
Return the number of sales by product category where the average recommended price is
R10 or more
SELECT COUNT(S.SalesID)
FROM tblSales AS s
INNER JOIN tblProducts AS P ON
S.productID = P.productID
GROUP BY p.catercory
HAVING AVG(P.recommendedPRice) >= 10
If you want to also check for recommended price greater than the average sales price you have to add following addtional checks
OR AVG(P.recommendedPRice) > AVG(S.salePrice)