Perimetrul gradinii:860m
Notam L=lungimea
l=latimea
2*(L+l)=860 => L+l=860/2=430 => l=430-L
L/2+25=2*l
L/2+25=2*(430-L)
L/2+25=860-2*L
L/2+25+2*L=860
L/2+2*L=860-25=835
Aducem la acelasi numitor in membrul stang amplifcand al doilea termen cu un 2
(L+4*L)/2=835
5*L=835*2=1670
L=1670/5=334m=lungimea
l=430-334=96m latime
Perimetrul unei gradini in forma depatrat=4*334=1336m