[tex]\left \{ {{n*x=60} \atop {(n-1)(x+8)=80}} \right. \\\left \{ {{x=\frac{60}{n} } \atop {(n-1)(x+8)=80}} \right. \\(n-1)*(\frac{60}{n}+8)=80\\n=-\frac{3}{2} \\n=5\\-\frac{3}{2}x=60\\5x=60\\x=-40\\x=12\\(n_{1}, x_{1})=(-\frac{3}{2}, -40)\\(n_{2}, x_{2})=(5, 12)\\\left \{ {{60=60} \atop {80=80}} \right. \\\left \{ {{60=60} \atop {80=80}} \right. \\(n_{1}, x_{1})=(-\frac{3}{2}, -40)\\(n_{2}, x_{2})=(5, 12)[/tex]
