Answer :
[tex]x+ y = 17\\ x=y-5 \\ \\y-5+y=17\\x=y-5\\\\2y=17+5\\x=y-5\\\\2y=22\ \ /:2 \\x=y-5\\\\y=11 \\x=11-5\\ \\y=11 \\x=6 \\\\Answer : \ are \ the \ two \ numbers \ 11 \ and \ 6[/tex]
[tex]x + y = 17 \\ x = y - 5 \\ \\ y - 5 + y = 17 \\ 2y = 17 + 5 \\ 2y = 22 \\ y = 22/2 \\ y = 11 \\ \\ x = y - 5 \\ x = 11 - 5 \\ x = 6 \\ \\ \left \{ {{y=11} \atop {x=6}} \right. [/tex]