3 inches is just 3/12 or 1/4 foot
the border minuses area
so
we have
the area=legnth times wdtih
the inside length and width are
length-2border and width-2border
because the border is on both sides
so
6-2 times 1/4=6-0.5=5.5
4-2 times 1/4=4-0.5=3.5
so the demotions inside the border are 5.5ft and 3.5ft
and the area is 19.25 square feet
