Q2. A rectangular pool 20m long by 12m wide is edged on all four sides with a grass strip 8m wide. Find the area of the grass.
subtract the area of the pool from the total area
(20+16)(12+16) - 20*12 = 768 m^2
or, multiply the perimeter by 8:
2(20+12)*8 = 512 ft^2
?? what's missing? The 4 corners, which stick out past the ends:
4*8^2 = 256
and 512+256 = 768
Or, just extend the dimensions by the border width:
2(20+8 + 12+8) = 768
see those pesky 4*8^2 terms hiding in there?