Ответ:

2EC

Объяснение:

АВ + СD - AC + BC - BE - CE = (AB + BC) + CA + EC + BC + EB =

AC + (EC + CA) + (EB + BC) = AC + EA + EC = (EA + AC) + EC = EC + EC = 2EC

-AC = CA

-CE = EC

-BE = EB