# SAT Data - Tables

**Discrete Mathematics**Level 1

\[\begin{array}{|c|c|c|c|c|} \hline & \text{High School} & \text{Middle School} & \text{ Total}\\ \hline \text{Boys} & a & 2b & X\\ \hline \text{Girls} & 2a & b & Y\\ \hline \text{Total} & M & N & T\\ \hline \end{array}\]

In the table above, each letter represents the number of students in that category. Which of the following equals \(M-N?\)

(A) \(\ \ X\)

(B) \(\ \ Y\)

(C) \(\ \ 3(Y-X)\)

(D) \(\ \ \frac{T}{3}\)

(E) \(\ \ X+Y\)