diluting for volume - maths question

hi all,
quick question about diluting beer. i have a saison that started at 1.048 which i was hoping to get down to 1.008 for a beer around 5.3%abv ... however that saison yeast is a real beast and it's down to 1.001 or 6.2%abv - not a disaster i'm sure you'll agree but i prefer my saisons on the light side concerning alc vol.
my question is this, i have 28l ready for bottling but i want to use the sugar addition for carbonation to add enough boiled water to bring the abv down to 5.3% ... and as i'm absolutely shite at maths, can anyone give me the quantity i'd need to hit the right abv and pass on a handy formula (written for a 5yr old is possible) that i can maybe use in future
cheers all !
jon

Here it is in words:
If you have 28 liters at 6.2% Alcohol by Volume, that means that the volume of alcohol is (6.2/100)*28 = 1.736 liters. If you want to take that volume of alcohol and make a solution that is 5.3% ABV, then the total volume of liquid would be 1.736/(5.3/100)=32.75 liters. Since  you have 28 liters now, you need to add 32.75-28 = 4.75 liters of water.

The formula is:
Va=V1*(A1/A2-1)
Va=volume to add, V1=original volume, A1=original ABV, A2=desired ABV. using the numbers above.
Va=28*(6.2/5.3-1)=4.75

thanks gigafemto,
really appreciate your assistance, this is exactly what i was hoping for  !
i was actually able to follow your reasoning on the first part and the second formula is really easy to use so thanks again for the help. if ever you're in switzerland and fancy a weak-ish saison, drop me a line
cheers,
jon

You're welcome. It is always a pleasure to help someone with issues like this. I am not planning to go to Switzerland anytime soon, but I will be hiking in Hungary, Austria and Slovenia this summer. That is a bit east of you, but do you have any suggestions on good beer to drink when I am there? Last spring my wife and I walked across England and enjoyed sampling local brews along the way, so we hope we can do the same this year.

is there a bad beer to drink
shamefully i don't have any knowledge of beers from that region, however you are sure to find great local pilsners, weizens, and bocks in that region.
thanks again for your help and enjoy your trip !
jon