batch decimal calculator failed attempt

set /p cost=-
cls
if %cost%==0 set "cost=nul"

set /a est=%hours%*%pph%

REM Sorting cents
set /a estcent=%hours%*%pphc%
set /a estcentf=%estcent%/10
cls

REM Sorting net earn

set centofcost=%cost:~-2%
REM gets all but the last 2 (the cents) of the cost
set allbutlast2=%cost:~0,-2%

if NOT %cost%==nul set /a net=%est%-%allbutlast2%
if NOT %cost%==nul set /a centofnet=%estcentf%-%centofcost%

REM if i spent nothing on food and drink, set the net to what i normally earn
if %cost%==nul set "net=%est%.%estcentf%"
if %cost%==nul set cost=0

if not exist %loc% MD %loc%
set date3=%date:~0,-10%
if %date3%==MON set "break=echo.^ "

::======
::test shit
::======



::==The other thing | dont touch this. not needed
set fullpay=%est%.%estcentf%
::==

set "cotn=%centofthenet%"
set "netvar=%net%"

::==if the cent of netpay is below 0, add 100 and minus 1 from dollar of net pay
::if %cotn%==LEQ 1 (
::set /a centofnet=%cotn%+100
::set /a net=%netvar%-1
::)

::== How much I earned after taking off what I spent on food
set "netpay=%net%.%centofnet%"