Question 91740
 -3x+a-b  [combine like-terms]
-3x+a-b=0  [set the expression equal to zero and solve for the x-term]
-3x+a-a-b=0-a
-3x-b=-a
-3x-b+b=-a+b
-3x=-a+b
{{{((-3x/1)(1/-3))}}}={{{((1/-3)(-a+b))}}}
x={{{(-a/-3 + b/-3)}}}
x={{{(a/3-b/3)}}}
x={{{(a-b)/3)}}}