I need to sum all of the cells to the right of a dropdown category anywhere on the page

Good morning,

I am creating an expense budgeting sheet where the user can select an expense category in a dropdown, and to the right of the columns with the dropdown option, there is a column for the expense costs. I have multiple sections for each month, so twelve columns with dropdown option and twelve columns with the costs (which are to the right of the dropdowns)

What I want to do is have a section that sums up the category expenses throughout the year. So even though expenses can appear in any month section, I want them to be totaled in a different section. I assume it would be a SUMIF formula...