L = 4X
B = 2X
G = X
5 gomas, 30 boligrafos y 2 libretas
Pago total = 73
5 (X) + 30 (2X) + 2 (4X) = 73
5X + 60X + 8X = 73
73X = 73
X = 73/73
X = 1
Entonces :
L = 4X ----------------------- L = 4 euros
B = 2X ----------------------- B = 2 euros
G = X ------------------------ G = 1 euro