Answer:
[tex]x=-10[/tex]
Step-by-step explanation:
[tex]-x+1=x+21[/tex]
Subtract 1 from both sides:
[tex]-x+1-1=x+21-1\\-x=x+20[/tex]
Subtract x from both sides:
[tex]-x-x=x+20-x\\-2x=20[/tex]
Divide both sides by -2:
[tex]\frac{-2x}{-2}=\frac{20}{-2}\\x=-10[/tex]
