lua, 137 bytes

Result

WA

Duration

484ms

Code [DL]

a={}for i=-3,8 do a[i]=io.read("*n")-a[i%3-3]
print((a[0]*(a[4]*a[8]-a[5]*a[7])+a[1]*(a[5]*a[6]-a[3]*a[8])+a[2]*(a[3]*a[7]-a[4]*a[6]))/6)

stdin

27 70 56
97 72 78
62 02 55
80 70 59

stdout

stderr

/usr/bin/lua5.3: /volume/CODE:2: 'end' expected (to close 'for' at line 1) near <eof>

strace