group by query with string manipulation

[jonathanpatton]

I'm running this query to get a count of categories I have in a field that contains 
aircraft categories.

SELECT  substring(category,10), count(*)
FROM `links` where category like 'Aircraft/Sales%'
group by category order by category

and getting these results:

---------------------------
Sales/Dealers        7
Sales                    203


I would like to get these results:

-------------------------------------
Sales                210


but am not sure how to manipulate the category field to do this. Thanks in advance.