Question

(k-m) + (2k -n) +(n + 2m) + (m-k ) ?

Answer 1

(k-m) + (2k -n) +(n + 2m) + (m-k ) =

k - m + 2k –n  + n + 2m + m-k  = (k + 2k – k) + (-m + 2m + m) (-n + n) = 2k + 2m = 2(k + m)