FORECAST FORMULA with a lot of tables.

Yo,

In the example i have made three tables. And in the fourth table i want to predict the trend with the (FORECAST or TREND) formulas.

I think the known x's are 1-1-14(1), 8-1-14(2), 15-1-14(3). Or is the type?

I think the future X is the next week, so it would be 22-1-14 (4).

The know y's are the figures beneath the headers TYPE 1 and TYPE 2, in the tables.
The known y's in the TYPE 1 are (2,3,4).
The known y's in the TYPE 2 are (1,2,4)

So the FORECAST y would be 5 for TYPE 1.
The FORECAST y would be 8 for TYPE 2.

This example is simple then then the real version, but you don't have to worry about the real-life situations.

Just how would you use the FORECAST-formula in excel for this if you don't alter the tables????

You shouldn't alter them, because instead of three sheets i have 2400 sheets.