[tex]the \ first \ number:\ \ x \\the \ second \ number: \ \ y\\\\\begin{cases}x+y=30 \\ x-y=50 \end{cases}\\------ \\2x=80 \ \ / :2\\x=40[/tex]
[tex] 40+y=30 \\y=30-40\\y=-10 \\ \\ Answer: \\\ \ the \ first \ number:\ \ 40 \\the \ second \ number: \ \ (-10)\\ \\ check:\\40-10=30\\ \\30=30\\L=R\\\\40-(-10)=50\\40+10=50\\50=50\\L=R [/tex]
