lua, 126 bytes

Result

WA

Duration

494ms

Code [DL]

a={}for i=-3,8 do a[i]=io.read("*n")-a[i%3-3]end
[b,c,d,e,f,g]=a[3:8]
print((a[0]*(c*g-d*f)+a[1]*(d*e-b*g)+a[2]*(b*f-c*e))//6)

stdin

66 33 92
07 30 15
25 33 59
21 75 41

stdout

stderr

/usr/bin/lua5.3: /volume/CODE:2: unexpected symbol near '['

strace