Răspuns :
P = 2(L + l) = 420
L = 5 * l
2(5 l + l) = 420 | : 2
6 l = 210
l = 210 : 6
l = 35 cm latimea
L = 5 * 35
L = 175 cm
L = 5 * l
2(5 l + l) = 420 | : 2
6 l = 210
l = 210 : 6
l = 35 cm latimea
L = 5 * 35
L = 175 cm