Step-by-step explanation:
[tex]\dfrac{-3}{(x+2)(x-5)}\qquad\text{use FOIL:}\ (a+b)(c+d)=ac+ad+bc+bd\\\\=\dfrac{-3}{(x)(x)+(x)(-5)+(2)(x)+(2)(-5)}\\\\=\dfrac{-3}{x^2-5x+2x-10}\qquad\text{combine like terms}\\\\=\dfrac{-3}{x^2-3x-10}[/tex]
[tex]\dfrac{64x-8x^2}{10x-80}=\dfrac{-8x(x-8)}{10(x-8)}\qquad\text{cancel}\ (x-18)\\\\=\dfrac{-8x}{10}=-\dfrac{8x:2}{10:2}=-\dfrac{4}{5}x[/tex]
