[tex]\it ab=5580\ \ \ \ (*)\\ \\ a(b+6)=5850\Rightarrow ab+6a=5850\stackrel{(*)}{\Longrightarrow}\ 5580+6a=5850|_{-5580} \Rightarrow\\ \\\Rightarrow 6a = 270|_{:6} \Rightarrow a = 45\\ \\ a=45 \stackrel{(*)}{\Longrightarrow}\ 45b=5580 \Rightarrow b=5580:45 \Rightarrow b=124[/tex]
