Question 41793
{{{drawing(400,300,-25,50,-25,50,
line(0,0,25,0),
line(25,0,25,10),
line(25,10,0,10),
line(0,10,0,0),
line(-5,-2.5,30,-2.5),
line(30,-2.5,30,12.5),
line(30,12.5,-5,12.5),
line(-5,12.5,-5,-2.5),
locate(0,0,A),
locate(25,0,B),
locate(25,10,C),
locate(0,10,D),
locate(-5,-2.5,E),
locate(30,-2.5,F),
locate(30,12.5,G),
locate(-5,12.5,H)
)
}}}

Rectangle ABCD represents the swimming pool.
Rectangle EFGH represents the swimming pool surrounded by the concrete path.
AB = CD = 25 m and BC = DA = 10 m
EF = GH = 25 + 2x5 = 35 m and FG = HF = 10 + 2x2.5 = 15


Area of the outer rectangle = 35 x 15 = 525 {{{m^2}}}.
Area of the inner rectangle = 25 x 10 = 250 {{{m^2}}}.
So, area of the concrete border = 525 - 250 = 275 {{{m^2}}}.