Respuesta :

1) If x=11 then y and z must be 12 and 13 respectively. So the average of x, y, and z would be (11+12+13)/3 = 12

2) If (y+z)/2 = 12.5 then we can see that y = 12 and z = 13. So x would be 11. It's the same as first question so again (11+12+13)/3 = 12
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