The diagram above (sorry my diagram isnt too great..) contains black and white tiles in a diamond formation. There are 7 tiles across and 25 tiles in total. Now I need to find how many tiles there would be in total, if the number of tiles across was 149. The formula I am using is n+x^2/y

So for the 7 across, the formula would be 7+x^2/y = 25

The only problem is, I cant work out what x and y are.

If you could help me finding what x and y are, that would be greatly appreciated.

Holly.