Question 448534
{{{x^2-2x+5x-(-x^2+7x)}}}



{{{x^2-2x+5x-(-x^2)-7x}}}



{{{x^2-2x+5x+x^2-7x}}}



{{{(x^2+x^2)+(-2x+5x-7x)}}}



{{{2x^2-4x}}}



So {{{x^2-2x+5x-(-x^2+7x)=2x^2-4x}}}