What’s the fastest way of helping these students?

Thanks to Anna for the submissions.

In case you’re having trouble reading the kid’s work, and because the top of the question is cut off, I’m going to reproduce the problem in text below the image:

Question: What is the product of $\frac{x^2-1}{x+1}$ and $\frac{x+3}{3x+3}$?

Answer: $\frac{3x^2-3}{3x+3}*\frac{x+3}{3x-3}$

$\frac{3x^2+9}{9x+9} \rightarrow \frac{1x^2+3}{3x+3}$

The usual: What does he know, what doesn’t he know, and what would you do next?