7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7

Respuesta:
0
Explicación:
7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7 7-7=0