A Variable expense is a type of expense that may vary from month to month. This type of expense includes things like electricity, groceries, clothing, and gas. When it comes to the groceries, it is considered to be a variable expense only if the household need the items that are purchased.
I can't seem to find a good way to make it more connected so I'll just have to tell you. The ∞ is above the ∑, while the i = 1 is under it. That is all one thing. The rest is followed as normal, and it is all next to the ∑
