\(ƯCLN\left(a,b\right)=12\Leftrightarrow\left\{{}\begin{matrix}a=12k\\b=12q\end{matrix}\right.\left(k>q;k,q\in N\text{*}\right)\\ a+b=96\\ \Leftrightarrow12\left(k+q\right)=96\\ \Leftrightarrow k+q=8\)
Mà \(k>q;\left(k,q\right)=1\)
\(\Leftrightarrow\left(k;q\right)\in\left\{\left(7;1\right);\left(5;3\right)\right\}\\ \Leftrightarrow\left(a;b\right)\in\left\{\left(84;12\right);\left(60;36\right)\right\}\)