Respuesta :

1 - 2 = 1      3 - 4 = 1     5 - 9 = 4     9 - 9 = 0     7 - 14 = 7       21  - 0 = 21     8 - 12 = 5         4 - 85 =  81       x is 8 and z is 5.     x - z = 3          d is 2 and 8 is w and 17 is y.      d - w - y = 7