First of all, move the terms so that all those who involve [tex]x[/tex] are on one side, and all the costants are on the other:
[tex]29 + 15x = -x - 3 \iff 15x+x=-29-3[/tex]
Sum like terms:
[tex]15x+x=-29-3 \iff 16x=-32[/tex]
Divide both sides by 16:
[tex]x=-2[/tex]
