I need help with adding.

[ThermicKestrel]

Im coding a .bat game and I need a way to increase/decrease health and money. I just want a smallish command instead of:

if %money%=05 set %money% 00
if %money%=10 set %money% 05
if %money%=15 set %money% 10
if %money%=20 set %money% 15
if %money%=25 set %money% 20
if %money%=30 set %money% 25

and etc. Is there just a command that subtracts or adds a specific number to a variable?

[Squashman]

set /a money-=5