\(\dfrac{25}{121}+\left(-\dfrac{28}{13}+\dfrac{15}{13}\right)=\dfrac{25}{121}+-\dfrac{13}{13}=\dfrac{25}{121}-1=\dfrac{25}{121}-\dfrac{121}{121}=-\dfrac{96}{121}\)
\(\left(\dfrac{25}{121}+\dfrac{-28}{13}\right)+\dfrac{15}{13}=\dfrac{25}{121}-\dfrac{28}{13}+\dfrac{15}{13}=\dfrac{25}{121}-\left(\dfrac{28}{13}-\dfrac{15}{13}\right)=\dfrac{25}{121}-1=-\dfrac{96}{121}\)