Subtraction - major confusion

[Bitlost]

My Y2 DD is learning subtractions.

In the past, to calculate say 25-12, she'd write:
25-12=
20+5-10-2=
10+3=
13

I don't like it but at least it's correct.

Today the teacher corrected her homework and wrote:
25-12=
20+5-10+2

To me, the method given by the teacher today is wrong without the use of parenthesis, which I don't expect kids to know in y2 by the way. Using this new method, DD will rightly arrive to 17 as she will add 5 and 2 but it's of course the wrong answer to the initial question.

Which method do your kids use?

Thank you.

Irvine: I sometimes dont know whether her explanation is ok -"and meet the teacher's requirement either but always I assume it must be the clearest for the dumpiest to be able to understand why it should be the result. I have to admit though she hasnt been very good at it yet. We are working on it though