a) $\dfrac{-11}{25}=\dfrac{-6}{25}+\dfrac{-1}{5}$
$\dfrac{-11}{25}=\dfrac{-2}{5}+\dfrac{-1}{25}$
$\dfrac{-11}{25}=\dfrac{-8}{25}+\dfrac{-3}{25}$
b) $\dfrac{-11}{25}=\dfrac{2}{5}-\dfrac{21}{25}$
$\dfrac{-11}{25}=\dfrac{1}{25}-\dfrac{12}{25}$
$\dfrac{-11}{25}=\dfrac{3}{5}-\dfrac{26}{25}$