Question

а-(b-(c-d))
a-(d+(c-(d-k)))

Answer 1

$a-(b-(c-d))=a-(b-c+d)=a-b+c-d$
$a-(d+(c-(d-k)))=a-(d+(c-d+k))=a-(d+c-d+k)=$
$=a-(c+k)=a-c-k$

Answer 2

2пр:=a-d+c-d+k=a-2d+c+k. 1пр:=а-b-c+d