Using Statement-I alone: Statement-I tells us that the sum of the marks scored by P and Q is equal to the sum of the marks scored by R and S. This does not provide any direct information about whether P scored more marks than Q. Thus, Statement-I alone is insufficient to answer the question.

Using Statement-II alone: Statement-II tells us that the sum of the marks scored by P and S is more than the sum of the marks scored by Q and R. However, this does not directly answer whether P scored more marks than Q. Therefore, Statement-II alone is also insufficient.

Combining both Statements: From Statement-I, we know that $P + Q = R + S$, and from Statement-II, we know that $P + S > Q + R$. Even with both statements, we cannot definitively determine if P scored more marks than Q because there is no direct relationship between P and Q's individual scores. Hence, combining both statements does not provide an answer.