vim, 191 bytes

Result

WA

Duration

524ms

Code [DL]

00000000  56 47 4a 3a 6c 65 74 20  6c 3d 6d 61 70 28 73 70  |VGJ:let l=map(sp|
00000010  6c 69 74 28 67 65 74 6c  69 6e 65 28 31 29 2c 27  |lit(getline(1),'|
00000020  20 27 29 2c 27 73 74 72  32 6e 72 28 76 3a 76 61  | '),'str2nr(v:va|
00000030  6c 29 27 29 0a 3a 66 6f  72 20 69 20 69 6e 20 72  |l)').:for i in r|
00000040  61 6e 67 65 28 39 29 0a  6c 65 74 20 6c 5b 69 2b  |ange(9).let l[i+|
00000050  33 5d 2d 3d 6c 5b 69 25  33 5d 0a 65 6e 64 66 6f  |3]-=l[i%3].endfo|
00000060  72 0a 43 12 3d 28 6c 5b  31 31 5d 2a 28 6c 5b 37  |r.C.=(l[11]*(l[7|
00000070  5d 2a 6c 5b 33 5d 2d 6c  5b 34 5d 2a 6c 5b 36 5d  |]*l[3]-l[4]*l[6]|
00000080  29 2b 6c 5b 31 30 5d 2a  28 6c 5b 33 5d 2a 6c 5b  |)+l[10]*(l[3]*l[|
00000090  38 5d 2d 6c 5b 35 5d 2a  6c 5b 36 5d 29 2b 6c 5b  |8]-l[5]*l[6])+l[|
000000a0  39 5d 2a 28 6c 5b 34 5d  2a 6c 5b 38 5d 2d 6c 5b  |9]*(l[4]*l[8]-l[|
000000b0  37 5d 2a 6c 5b 35 5d 29  29 2f 36 0a 1b 5a 5a     |7]*l[5]))/6..ZZ|
000000bf

Disassembly

VGJ:let l=map(split(getline(1),' '),'str2nr(v:val)')<NL>:for i in range(9)<NL>let l[i+3]-=l[i%3]<NL>endfor<NL>C<C-R>=(l[11]*(l[7]*l[3]-l[4]*l[6])+l[10]*(l[3]*l[8]-l[5]*l[6])+l[9]*(l[4]*l[8]-l[7]*l[5]))/6<NL><Esc>ZZ

stdin

45 07 78
45 11 17
66 78 62
72 20 30

stdout

45 07 78 45 11 17 66 78 6222649

stderr

strace