Question 362279
{{{n^2-4n-3n^2+7n+5n^2=(n^2-3n^2+5n^2)-4n+7n}}}
{{{n^2-4n-3n^2+7n+5n^2=3n^2+3n}}}
{{{n^2-4n-3n^2+7n+5n^2=3n(n+1)}}}