I have a huge data frame that looks like this:

and I want to sum the cells in column V9 according to V3; for example, I want to sum every V9 cell when V3=="Acrelândia".
I have a huge data frame that looks like this:

and I want to sum the cells in column V9 according to V3; for example, I want to sum every V9 cell when V3=="Acrelândia".