For this case we have the following equation:

The steps used by Viktoriya to solve are:
Step 1:
Distributive property:

Step 2:
Combine similar terms:

Step 3:
Simplify:

Viktoriya's error is in the conclusion of the problem.
The equation has no solution, because:
Left side ≠ right side
Answer:
Viktoriya's error is: the equation has infinitely many solutions.