Need help explaining method of calculation for a school question for my $10$ year old

Question

A family friend sent us an example question that said a child starting secondary / high school would have in their first year. We tried showing it to my 10 year old who was unable to do it, after having a look myself I don't know either. The question is as follows:

Abe, Ben and Ceri's total score playing a video game was $4665$. Ben scored $311$ fewer than Abe but $3$ times more than Ceri. How many points did Ceri score?

I've seen what claims to be the answer, but I couldn't explain how it was right. Can anyone explain, please?

Answer 1

Let's remove $311$ points from Abe, without affecting Ben and Ceri. So now the total is $4665 - 311 = 4354$, and Abe and Ben each have $3$ times as much as Ceri. Together, Abe, Ben and Ceri have $3+3+1=7$ times as much as Ceri. So Ceri has $4354/7 = 622$ points.

Answer 2

Let the scores be $A,B,C$ with the obvious notation. Then we have $$A+B+C=4665\quad\&\quad B=A-311\quad \&\quad B=3C\implies$$ $$\implies A+(A-311)+\frac {A-311}3=4665$$

Can you finish from here?