Look at the topic you sent, and the result is 4+3-2=5. However, there are several possibilities:

1, you didn't write the topic completely, causing misunderstanding;

2. The teacher misjudged and missed the judgment. Because teachers are human beings, there can be no mistakes. In this case, you can refer to whether other children answered this question in this way, see if it is correct, and then discuss it with the teacher. This is not only a matter of course, but also an abrupt past.