Say that you're thinking of number [tex] x [/tex]
You multiply it by 8, and have [tex] 8x [/tex]
You add -1 (i.e., you subtract 1) and have [tex] 8x-1 [/tex]
This equals -17, so you have
[tex] 8x-1=-17 [/tex]
Add 1 to both sides
[tex] 8x=-16[/tex]
Divide both sides by 8:
[tex] x=-2 [/tex]
So, you were thinking of -2.
