In the first one, you are using 2 conditions (Mathematical&&Scoreofchinese) with ONE "if" statement.

In the second one, you're first looking to confirm a first condition (Mathematical) in a if statetement, before confirming the second one (Scoreofchinese) with a second statement.

Same result. You would choose one over the other depending on your need. Be sure to read also about the "||" (OR)

Are these two expressions the same?