Answer:
[tex]x_1=0.14\\x_2=-85.14[/tex]
Step-by-step explanation:
1. You have the following expression given in the problem above:
[tex]12+12x=x^{2}-7x+104x[/tex]
2. Then, you need to add like terms, so you have:
[tex]0=x^{2}+85x-12[/tex]
3. Apply the quadratic formula, as following:
[tex]x=\frac{-b+/-\sqrt{x^{2}-4ac}}{2a}\\a=1\\b=85\\c=-12[/tex]
Then:
[tex]x_1=0.14\\x_2=-85.14[/tex]