Answer :

luana
[tex]9x+10=12x-11[/tex]
We put 12x on the left side and 10 on right side
[tex]9x-12x=-11-10[/tex]
Now we add x and free numbers 
[tex]-3x=-21[/tex]
And our result is:
[tex]x=7[/tex]

[tex]3(x-8)=5x+7[/tex]
[tex]3x-24=5x+7[/tex]
[tex]3x-5x=7+24[/tex]
[tex]-2x=31[/tex]
[tex]x=- \frac{31}{2} [/tex]
konrad509
[tex]9x+10=12x-11\\ 3x=21\\ x=7\\\\ 3(x-8)=5x+7\\ 3x-24=5x+7\\ 2x=-31\\ x=-\frac{31}{2} [/tex]