If you 31 marks out of 40 questions in a sats test what level is that?

A score of 31 out of 40 on a SATS test is approximately 77.5%. However, the specific level (e.g., Level 4, Level 5, etc.) isn't determined by a simple percentage. The level depends on the specific test, the age of the student, and the standards set by the testing authority. There's no single universal scale. You need to consult the marking scheme or standards provided with the test itself to determine the corresponding level.