Question

{ a+b-c- { a - b +c - { a- b+ c - ( a-b ) }}}

Answer 1

[a+b-c-[a-b+c-[a-b+c-(a-b)]]]

[a+b-c-[a-b+c-[a-b+c-a+b]]]

[a+b-c-[a-b+c-c]]

[a+b-c-a+b]

2b-c es la respuesta espero te ayude