How Do I Add To A Variable?

How do you add to a variable? By that I mean how do you do like (Variable Name) + (Given Number). I want it so that every time a sprite does a certain thing it adds to the variable but I don't know how to make variables add.

There is an option under system event, "add to variable".

There is an option under system event, "add to variable".

Yeah sorry I phrased that wrong I mistook the bullet speed for a variable because I used a variable for it originally for a power thing, aaanyway, is there a way to subtract from the bullets speed? rekjl

Yes, you can...haha by using a variable to control the speed. For example, every tick, set bullet speed to variable1. Than from there on, just adjust the variable1 according to what you need.

set object.bullet.speed = object.bullet.speed - X