Помогите пожалуйста! (№4 и 5)

4)
$\left \{ {{3x\ \textgreater \ 1} \atop {-x\ \textless \ 3}} \right. , \left \{ {{x\ \textgreater \ 1/3} \atop {x\ \textgreater \ -3}} \right. , x\ \textgreater \ 1/3$

5)
$\left \{ {{x^2-9y^2=150} \atop {x+3y=50}} \right. , \left \{ {{(x-3y)(x+3y)=150} \atop {x+3y=50}} \right. , \left \{ {{50(x-3y)=150} \atop {x+3y=50}} \right. , \left \{ {{x-3y=3} \atop {x+3y=50}} \right. ,2x=53,\\x=26.5\\y=\frac{50-53/2}{3}=\frac{47/2}{3}=\frac{47}{6}\\\\(\frac{53}{2}, \frac{47}{6})$