Ответ:

2bc / (2b + c)^2

Пошаговое объяснение:

2b / (2b + c) - 4b^2 / (4b^2 + 4bc + c^2) =

2b / (2b + c) - 4b^2 / (2b + c)^2 =

(2b(2b + c) - 4b^2 ) / (2b + c)^2 =

(4b^2 + 2bc - 4b^2) / (2b + c)^2=

2bc / (2b + c)^2