[tex] \frac{12-n}{7} = - 1[/tex]
Multiply cross
[tex]12-n = 7*(-1)[/tex]
[tex]12-n = -7[/tex]
Number with incognito are to the left of the equality and numbers without incognito are to the right, remembering that when changing of side changes the signal.
[tex]-n = -7-12[/tex]
[tex]-n=-19[/tex] simplify by (-1)
[tex]\boxed{n = 19}[/tex]
Confirm that the solution is correct:
[tex] \frac{12-n}{7} = - 1[/tex]
[tex]\frac{12-19}{7} = - 1[/tex]
[tex]\frac{-7}{7} = - 1[/tex]
[tex]\boxed{-1=-1}(TRUE)[/tex]
Answer:
[tex]\boxed{n = 19}[/tex]
