Word problems can feel a little tricky because there is a lot of information to keep track of, but once we look at this one together, I hope it will start to get easier.
I like to use a highlighting strategy to keep track of the important information. I will bold every word or number that lets us know how many children will be coming to the party:
Matthew invited 11 children from school and 6 children from the neighborhood. Including Mathew and his two brothers, how many children will be at the party?
Now all we need to do is add:
11 children from school + 6 children from the neighborhood + Mathew + two brothers =
If you complete the addition, you will have your answer! Good luck and happy solving.