{x+y=a−3x−y=3a−5{\displaystyle {\begin{cases}x+y=a-3\\x-y=3a-5\\\end{cases}}}
2x=a−3+3a−52x=4a−8x=2a−4{\displaystyle {\begin{aligned}&2x=a-3+3a-5\\&2x=4a-8\\&x=2a-4\\\end{aligned}}}
נציב את X במשוואה הראשונה : x+y=a−32a−4+y=a−3y=−a+1{\displaystyle {\begin{aligned}&x+y=a-3\\&2a-4+y=a-3\\&y=-a+1\\\end{aligned}}}
|2a−4|<10−10<2a−4>10{\displaystyle {\begin{aligned}&|2a-4|<10\\&-10<2a-4>10\end{aligned}}}
2a−4<102a<14a<7{\displaystyle {\begin{aligned}&2a-4<10\\&2a<14\\&a<7\\\end{aligned}}}
−3<x<7{\displaystyle {\begin{aligned}-3<x<7\end{aligned}}}
|−a+1|>3{\displaystyle {\begin{aligned}&|-a+1|>3\\\end{aligned}}}
−a+1<−3−a<−4a>4{\displaystyle {\begin{aligned}&-a+1<-3\\&-a<-4\\&a>4\\\end{aligned}}}
x<−2;x>4{\displaystyle {\begin{aligned}x<-2;x>4\end{aligned}}}
x<−2x>4−3<x<7{\displaystyle {\begin{aligned}&x<-2\\&x>4\\&-3<x<7\end{aligned}}}