help with areas addition please

hi everyone, im sorry about asking kinda simple questions but im just beginning with gh, the problem is that i have created a sequence of planar surfaces, but then i use the "area" component, wich creates a list with all surface´s areas, then i need a total area, but i cant figure out how to add all those list elements, i already tried mass addition but it didn´t work.

any help will be really apreciated

thx