Respuesta :

don't forget the invisble negative ones to distriute
do inside to outside

{n-1-1[n-1-1(n-1)]}
do inside
{n-1-1[n-1-n+1]}
simplify inner parenthasees
{n-1-1[n-n+1-1]}
{n-1-1[0]}
multply
{n-1-0}
add
n-1-0=n-1


it is n-1 simplified

{n - 1 - [n - 1 - (n - 1)]}

=n - 1 - n + 1 + n - 1

=n -1