Elena began to solve this equation:
12x + 6(4x + 3) =2(6x + 4) – 2
----------------------
3
12x + 6(4x + 3) = 3(2(6x + 4) - 2)
12x + 6(4x + 3) = 6(6x+ 4) – 6
12x + 24x + 18 = 36x + 24 - 6

When she got to the last line she stopped and said the equation is true for all values of x. How could Elena tell?​