I happen to own The Hardest Day and it gives a detailed breakdown for that day. Juhu provided the exchange rate for 10 july - 11 Aug:
So 6 FC fighters were lost to 110s but LW had lost 27 110s in combat.
On Aug 15 and 18, 24-25 Bf110s were lost and they downed 3 Hurricanes, for certain, but if we credit them with a couple of kills where the Luftwaffe fighter was not identified and give full, instead of partial, credit to GF, then we might get 22 Bf110 losses against 5 kills, for Aug 15 and 18. So the exchange rate for these dates runs from a probable 52 bf110s to 9 FC fighters, to a low of 49 bf110s to 11 FC fighters.
I'm sorry if it is not very flattering to the Bf110.