\(\Leftrightarrow\left(x-1\right)\left(y-3\right)=7\)
\(\Leftrightarrow\left(x-1;y-3\right)\in\left\{\left(1;7\right);\left(7;1\right);\left(-1;-7\right);\left(-7;-1\right)\right\}\)
hay \(\left(x,y\right)\in\left\{\left(4;10\right);\left(8;4\right);\left(0;-4\right);\left(-6;2\right)\right\}\)