Need help solve " We unsupport $((arith)) " Syntax Error

[Gururaja Hebbar K R]

Hi All,

I am using Busybox-1.10.2 (full patch applied) built with CodeSourcery
ARM926EJS toolchain to compile Busybox to run on customized arm
versatile board,

i am using few init scripts to run and while running /etc/init.d/rc i
get error as 

Syntax error: We unsupport $((arith))

when i checked the file, it had something like this

step=$(($step + $step_change))

I tried to remove the double brackets and make it look as 

step=$($step + $step_change)

this stopped the error to appear at  this point and started appearing at
other points. This file has a lot of such declarations.

I tried removing all those double brackets but i think its wrong to do
that.

Any help,advice, updates, changes is highly helpful

TIA

Regards
Gururaja