What is 5x + (x+8) = - 28-3x

First remove the parenthesis since you can't combine unlike terms.

5x+x+8=--28-3x

Then simplify

6x+8=-28-3x

Then add 3x to both sides

9x+8=-28

After, subtract 8 to both sides

9x=-36

Then divide both sides by - 9

x=-4