cy, 74 bytes

Result

WA

Duration

616ms

Code [DL]

"\\#{require'matrix';p Matrix[*$<.map{|x|[1]+x.split.map \&:to_i}].det/6}"

stdin

48 44 55
76 70 68
37 86 66
07 14 75

stdout

stderr

/root/cy.rb:566:in `eval': (eval):1: syntax error, unexpected &, expecting '}' (SyntaxError)
...ix[*$<.map{|x|[1]+x.split.map &:to_i}].det/6}"
...                              ^
	from /root/cy.rb:566:in `block in string'
	from /root/cy.rb:665:in `block in exec'
	from /root/cy.rb:660:in `each'
	from /root/cy.rb:660:in `exec'
	from /root/cy.rb:777:in `block (3 levels) in <main>'
	from /root/cy.rb:844:in `<main>'

strace