How we can determine whether is guess and check Q
Can you give me a tip

That’s a great question. Usually, I use GnC when I don’t have enough information. In this case, there are so many possibilities for Maths and Sc (90, 91, 92, ... 99) and Sc (70, 71, ... 79); we also need to make sure the total = 168 and that MA should be as large as possible. That’s why I decided to use Guess and Check.