X=3
Explanation-
(x-1)+(x-2)=3
x-1+(x-2)=3
x-1+x-2=3
Then collect the two like terms
x-1+x-2=3=
2x-1-2=3
Calculate the difference
x-1+x-2=3=
2x-3=3
———————
2x-3=3
Move the constant to the right-hand side and change its sign
2x=3+3
———————————————————-
2x=3+3
Add the numbers
2x=6
————————————————-
2x=6
Divide both sides of the equation by two
X=3
There you go. Have a great day! :)