How many cans of soda for 200 guests at a wedding reception if there will be bottled water and kegs of beer too?

It depends on how much beer those 200 people are willing to drink. But my guess is 40.

It's probably too late for you now, but 40 kegs would probably serve a small town. 1 keg contains ~15.5 gallons of beer. That's about 165 12oz cans of beer. Take a look at your guy to girl ratio. Guys will drink more than girls and you can maybe assume 1-2 beers per guy and 0-1 per girl each hour. This is also assuming your friends are all alcoholics...

Let's just assume an even split of 100 guys and 100 girls at a 4 hour party. Worst case scenario is you go through about 300 beers/hour for 4 hours. That's 1200 beers for this wicked awesome party. 1200/165 = 7 kegs. I have never in my life seen a party go through that many kegs.

That's an awful lot of beer that will cost a small fortune. I personally would not buy any more than 4-5 kegs. There are a lot of things you can't account for such as pre-gamers, beer haters, waiting lines and people that need to drive.

2 maybe 3 if this is a wedding reception think about the grooms buddies, are they a bunch of animals and still single, or are they a bunch of pompous a**holes that talk a big game but in actuality if their gf or wife sees the pink isod wearing douche bag anywhere near the keg she'll kick his a**.