Ok ok..so i that does my head in!! Any one else wanna solve this??

Its the space taken up by the slope that makes the difference by my calculation

slope is the same at middle and high end as is the length...this has got me beat!

That's a good one.

Clue
Two by three.

Five and eight help.

that does my head in too!

Thanks, I now have a headache.

i'm getting a migraine....eewww