Shell Programming and Scripting

$ a=10
$ b=13.5
$ printf "%.2f\n" $(((b-a)/b*100))
25.93

$ a=10
$ b=13.5
$ printf "%.2f\n" $(echo "scale=2\n(($b-$a)*100)/$b"|bc)
25.92

[[XXXXXXXXXXXXXXXXX]:~ 07:01:55 $]b=47
[[XXXXXXXXXXXXXXXXX]:~ 07:02:09 $]a=7
[[XXXXXXXXXXXXXXXXX]:~ 07:02:16 $]printf "%.2f\n" $(((b-a)/b*100))
0.00
[[XXXXXXXXXXXXXXXXX]:~ 07:02:20 $]printf "%.2f\n" $(((b-a)*100/b))
85.00
[[XXXXXXXXXXXXXXXXX]:~ 07:02:37 $]printf "%.2f\n" $(echo "scale=2\n(($b-$a)*100)/$b"|bc)
(standard_in) 1: illegal character: \
(standard_in) 1: parse error
0.00

printf "%.2f\n" $(echo -e "scale=2\n(($b-$a)*100)/$b"|bc)

$ printf "%.2f\n" 12.359
12.36