l=lățimea
L=lungimea
a)
2l+2L=32 cm /:2
l+L=16 cm
dar L=7l => 8l=16 cm /:8 => l=2 cm
L=7x2 => L=14 cm
b)
2l+2L=72 cm /:2
l+L=36 cm
dar L=11l => 12l=36 cm /:12 => l=3 cm
L=11x3 => L=33 cm
c)
2l+2L=120 cm /:2
l+L=60 cm
dar L=3/7xl => 10l:7=60 /x7
10l=420 cm /:10 => l=42 cm
L=42x3:7
L=6x3
L=18 cm
