Question

раскройте скобки 15-(7a+(4a-(a-9)))

Answer 1

$15-(7a+(4a-(a-9))) \ 15-(7a+(4a-a+9)) \ 15-(7x+(3x+9)) \ 15-(7x+3x+9) \ 15-(10x+9) \ 15-10x-9 \ 6-10x$

Answer 2

15-(7а+(4а-(а-9)))=15-(7а+(4а-а+9))=15-(7а+(3а+9))=15-(7а+3а+9)=15-(10а+9)=15-10а-9=6-10а