# [Jelly], [05AB1E], 6 bytes, score = \$\frac 6 8 = 0.75\$

 .Vq
 ɠV

[Try it online!][TIO-k4qretvb]

[Jelly]: https://github.com/DennisMitchell/jelly
[TIO-k4qretvb]: https://tio.run/##y0rNyan8/18vrJDr5IKw//8NtY0A "Jelly – Try It Online"

[Try it online 05AB1E!][TIO-hebexhq]

[TIO-hebexhq]: https://tio.run/##yy9OTMpM/f9fL6yQ6@SCsP//DRWMtAE

# Previous answer that does 3 languages:

## [Jelly], [Python 3], [05AB1E], 29 characters, score = \$\frac {29} {27} \approx 1.07\$

 exec(input( ))#}I.Vq
 1 ,1#ṛɠV

[Try it online Jelly!][TIO-k4qqrtbu]

[Jelly]: https://github.com/DennisMitchell/jelly
[TIO-k4qqrtbu]: https://tio.run/##y0rNyan8/z@1IjVZIzOvoLREQ0FTU7nWUy@skMtQQcdQ@eHO2ScXhP3/b6htDAA "Jelly – Try It Online"

[Try it online Python 3!][TIO-k4q0q4qi]

[Python 3]: https://docs.python.org/3/
[TIO-k4q0q4qi]: https://tio.run/##K6gsycjPM/7/P7UiNVkjM6@gtERDQVNTudZTL6yQy1BBx1D54c7ZJxeE/f9fUJSZV6JhqG2kCQA "Python 3 – Try It Online"

[Try it online 05AB1E!][TIO-k4qqvfv3]

[05AB1E]: https://github.com/Adriandmen/05AB1E
[TIO-k4qqvfv3]: https://tio.run/##yy9OTMpM/f8/tSI1WSMzr6C0RENBU1O51lMvrJDLUEHHUPnhztknF4T9/2@oYKQNAA "05AB1E – Try It Online"

In both cases, takes a program in the relevant language from STDIN and executes it, with any output going to STDOUT.