Simplify the expression $$(x^5+3x^2+3x^5)-(x^7+2x^2+6x^5).$$
To simplify this expression, I need to combine like terms and subtract them with the same degree of x. I also need to be careful with the signs, since there is a minus sign in front of the parentheses. I can rewrite the expression as $$x^5+3x^2+3x^5-x^7-2x^2-6x^5.$$ Now I can group the terms with the same degree of x together and subtract them: $$(-x^7)+(x^5+3x^5-6x^5)+(3x^2-2x^2).$$ I can simplify each group by adding or subtracting the coefficients: $$-x^7-2x^5+x^2.$$ This is the simplest form of the expression, so I am done. 