Answer
$$x=1.5a-1.5b$$
Work Step by Step
We're given:
$$x+2a-b=3(x+a)-2(2a-b)$$
First, distribute the scalar-vector multiplications on the right hand side:
$$x+2a-b=3x+3a-4a+2b$$
Next, add up the $a$ terms on the right:
$$x+2a-b=3x-a+2b$$
Subtract $3x$ from both sides to move all the $x$ terms to the left:
$$-2x+2a-b=-a+2b$$
Now subtract $2a-b$ from both sides to move all the $a$ and $b$ terms to the right:
$$-2x=-3a+3b$$
Lastly, divide both sides by $-2$, leaving us with:
$$x=1.5a-1.5b$$
