" Start with 200" ???
Frank, Czech Republic is on the Koruna, not the euro. A Koruna is worth about 5¢, so 200 Koruna is about $10. Food is cheap in the Republic, but not that cheap.
When I was there by myself for "3 days" (2 nights), I spent 24 czk for a metro ticket to get to my accommodations from the Hbf (hl.n.) the first day. The next day I bought an all day pass for everything in Prague for 110 czk.
I took out 3900 czk (about $200) from the ATM when I arrived and left with around 900 czk (about $35). That included 1300 czk cash for my room.
Breakfast was included with my night's lodging. The first night, I had a pretty nice dinner at a local restaurant. Dinner, two Pilners, and tip was 320 czk. The next day I had a nice lunch (more like a dinner) on the Capital Hill for 350 czk (food, beverages, and tip) and a light dinner for 200 czk. So I think, assuming you get breakfast with your room, 550-600 czk per day per person for meals would be about right, maybe a little more if you splurge.
So, is it 3 day's meals plus dinner the day you arrive, or a total of three days with only one full day plus dinner when you arrive and nothing the day you leave (if the hotel includes breakfast). You can add it up.
According to the website for the Airports Express bus from hl.n., the one way adult fare is 60 czk.