I was wondering how to convert my Data below to my Desired_output?
My Desired_output is a columsum of n_started and  n_finished columns for each district in Data.
Data = read.table(h=TRUE,text="
district grade n_started  n_finished
A        1     5          9
A        2     3          6
B        1     1          2
B        2     2          4
B        3     6          7")
Desired_output=
"
district  n_started  n_finished
A         5+3          9+6
B        1+2+6        2+4+7"
 
     
    