plss can someone help me with this problem and pls show work

-x-3=10 (combine like terms)
-x=13 (add 3 to both sides)
x=-13 (divide both sides by -1)
so you add 3 to the 10 since it is the opposite of a negative 3
then you subtract 6 from 13 since -6 it is the opposite of positive 6
then you divide both sides by -1
then it is x=-7