powershell, 316 bytes

Result

WA

Duration

1211ms

Code [DL]

$a =(Read-Host).Split();
$b =(Read-Host).Split();
$c =(Read-Host).Split();
$d =(Read-Host).Split();
$x=@()
$y=@()
$z=@()
foreach($i in 0..2){
$x+=$b[$i]-$a[$i]
$y+=$c[$i]-$a[$i]
$z+=$d[$i]-$a[$i]
}

echo(($x[0]*$y[1]*$z[2]+$x[1]*$y[2]*$z[0]+$x[2]*$y[0]*$z[1]-$x[1]*$y[0]*$z[2]-$x[2]*$y[1]*$z[0]-$x[0]*$y[2]*$z[1])/6)

stdin

29 29 26
15 09 59
42 30 68
53 93 72

stdout

29 29 26
15 09 59
42 30 68
53 93 72
9242

stderr

strace