#5 Languages, 32 / 5^3 = 0.28
###[Whitespace][ws], Brainfuck, Ruby, [Labyrinth][lab], Foo

Legend:

`£`: tab

`•`: space 

 puts•2;#4!@ -[>+<-----]>."5"•£
 £
 •£
 	
 	
##Explanation:

###Whitespace

(omitting ignored characters)

<kbd>space</kbd><kbd>space</kbd><kbd>space</kbd><kbd>tab</kbd><kbd>enter</kbd>: push a 1 onto the stack

<kbd>tab</kbd><kbd>enter</kbd><kbd>space</kbd><kbd>tab</kbd>: output the top of the stack 

###Ruby

Shouldn't need explaining. Prints 2, treats the rest of that line (ergo, the brainfuck program) as a comment, treats the rest of the file as empty.

###Brainfuck

Requires an interpreter that supports underflow. Underflows the first cell to 255 then uses that for a loop counter to generate 51, which is the ascii code for 3.

###Labyrinth

(omitting the last two lines for legibility because they are never reached)

 puts•2;#4!@ -[>+<-----]>"5".•£
 puts• skipped
 2 push 2 onto stack
 ; pop 2 from stack
 # push current stack depth (0) to stack
 4 push 4 to stack
 ! print top of stack as integer
 @ program terminates
 
###Foo

The only thing that affects output is "5", which prints 5.

[ws]:http://web.archive.org/web/20150523181043/http://compsoc.dur.ac.uk/whitespace/index.php
[lab]:https://github.com/mbuettner/labyrinth