Question

http://prntscr.com/2lkf42

Answer 1

do you know how to add and subtract?

Answer 2

yes

Answer 3

then start adding the values of CED, BEC and AED
after you do that, subtract BEC

in short, if you noticed that the result is similar to just adding CED and AED

Answer 4

even a five-year-old can do this task

have more confidence in your arithmetic skills, will you?