1.
a = Victoria
b = Aurora
a = b + 50
a + 8 = 3b
(b+50) + 8 = 3b
b + 58 = 3b
3b - b = 58
2b = 58
b = 29
a = 29 + 50
a = 79
2.
P - perimetro = valla = 156 m
L - largo = A +18
A - ancho
P = 2L + 2A
156 = 2(A + 18) + 2A
156 = 2A + 36 + 2A
4A = 156 - 36
4A = 120
A = 30 m
L = 30 + 18
L = 48 m
3.
P = perimetro = 48 cm
L1 = lados iguales
L2 = lado desigual
P = 2L1 + L2
L1 = L2 - 3
P = 2(L2 - 3) + L2
48 = 2L2 - 6 + L2
48 = 3L2 - 6
3L2 = 48 + 6
3L2 = 54
L2 = 18
L1 = 18 - 3
L1 = 15