Ok, giving it up .. all I can get from the current 149 is one stroke more out of it for 150


 Code:
function a($x)
   dim $v, $b, $
   while $x
       $ = left($x,1)
       $x = right($x,~)
       if $>!
           $v = ($=X^$="/")*10 + $ - ($="/")*$v
           $a = $a + ($b+($b<2))*$v
           $b = instr("/X",$)*($x<!) + $b/2
endfunction


Even with this one, only 150:

 Code:
function a($)
   dim $v, $b, $x, $c
   while $
       $x = left($,1)
       $ = right($,~)
       if $x>!
           $c = instr("/X",$x)
           $v = ($c>)*10 + $x - ($c=1)*$v
           $a = $a + ($b+($b<2))*$v
           $b = $c*($<!) + $b/2
endfunction


So I guess the 149 Version can't be optimized anymore.
Well played Jooel, thumbs up!
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