\(\dfrac{x}{4x-16}=\dfrac{x}{4\left(x-4\right)}=\dfrac{-5x}{20\left(4-x\right)}\)
\(\dfrac{1+x}{20-5x}=\dfrac{1+x}{5\left(4-x\right)}=\dfrac{4+4x}{20\left(4-x\right)}\)
\(\dfrac{x}{4x-16}=\dfrac{x}{4\left(x-4\right)}=\dfrac{5x}{20\left(x-4\right)}\\ \dfrac{1+x}{20-5x}=\dfrac{-\left(x+1\right)}{5\left(x-4\right)}=\dfrac{-4\left(x+1\right)}{20\left(x-4\right)}\)