a) \(\frac{x}{5}=\frac{-3}{y}\Rightarrow xy=5.\left(-3\right)\Rightarrow xy=-15\)
\(\Rightarrow x;y\)là cặp ước của -15
\(\Rightarrow\left(x;y\right)\in\left\{\left(1;-15\right);\left(-1;15\right);\left(-3;5\right);\left(-5;3\right)\right\}\)
b) \(-\frac{11}{x}=\frac{y}{3}\Leftrightarrow xy=\left(-11\right).3=-33\)
\(\Rightarrow x;y\)là cặp ước của -33
\(\Rightarrow\left(x;y\right)\in\left\{\left(-1;33\right);\left(1;-33\right);\left(-3;11\right);\left(3;-11\right)\right\}\)