Respuesta :

ax+b=3(x-a)

Distribute on the left side with the parentheses

ax + b = 3x - 3a

Now get the x on one side by itself 

Subtract 3x from both sides

ax + b - 3x = -3a

ax - 3x + b = -3a

x(a-3) = -3a

Divide both sides by (a-3)

x = -3a / a-3