Respuesta :
PLEASE MARK BRAINLIEST!
Answer:
B) the student found an incorrect common denominator
Step-by-step explanation:
The error was in the second step - 1/5x and 3/5x do not become 1x and 3x, it becomes 4/5x. That was the mistake.
I hope this helps!
The answer is A. The student did not multiply all terms by the common denominator.