P = 2×(L +l) = 128 m
L : 4 + l : 3 = 18 |×12
3×L + 4×l = 216
2×L + 2×l = 128 |×2
4×L × 4×l = 256
3×L + 4×l = 216
____________ ( - )
L = 40 ( lungimea)
3 × 40 = 120
l = (216-120):4 = 96 : 4 = 24 (latimea)
Verificare:
2×(40+24) = 2×64 = 128
40 : 4 + 24 : 3 = 10 + 8 = 18