You've got 3 as a coefficient on both sides, so you can divide both sides by 3 to cancel them out. Then you've got:
x + 4 = x - 5
You know that this can't have a solution because there is no value x where if you add 4 to it and subtract 5 from it, you'll get the same thing.
So, the problem with the equation is that the x values have to be the same, but the constant numbers added/subtracted are different. (If you liked this answer please rate it as brainliest!! thank you!!)
