Hi there!
In the second step, there is no x in 3b to factor out.
In the second step, "x" is factored from ax - 3b which is incorrect.
In order to factor out a variable, both terms must contain "x". In this instance, however, 3b does not contain an "x" variable.
To properly solve, you would do:
10 = ax - 3b
Isolate the x variable:
10 - 3b = ax
Divide both sides by a:
(10 - 3b) / a = x.