If the sides were 2 and 3 then using Pythagoras the diagonal would be sr(2^2 + 3^2) = sr(13)
The actual diagonal is 8 inches so the sides need to be scaled by 8/sr(13)
The screen area will be 2 x 8/sr(13) x 3 x 8/sr(13) = 29.539....
Rounded to nearest sq.inch this is 30 sq.inch