Question

What is the answer and how do i solve ?

Answer 1

$\bf -6n+(-12)+4n\implies -6n-12+4n\implies -6n+4n-12\implies -2n-12 \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ 4(n-3)-6n\implies 4n-12-6n\implies -2n-12~~\checkmark \\\\\\ 2(2n-6)\implies 4n-12~~\bigotimes$