Getting values from different columns in one formula

Say I have 20 different X values and 20 different Y values, and I want to make a least squares regression.

But all the X values are spread out over different columns (and so are the Y values).
So lets say the X values could be:
A1:A6, D1:D6, F1:F6.
And the Y values are B1:B6, E1:E6, G1:G6.

The only way I know how to do a linear regression would be to copy past the X (and the Y values) to the same column, so the D1:D6 x values would be placed at A7:A12 and the F1:F6 values would be placed at A13-A18.
But is there any way in which I can avoid this time consuming copy paste problem?

I attached an excel file to describe the problem. Hope someone (smart) can help me.