Answer: 60 students
Let the number of students be \(x\).
\[\frac{540}{x} - \frac{540}{x + 30} = 3\]\[540 \times 30 = 3x(x + 30)\]\[x^2 + 30x - 5400 = 0\]\[(x + 90)(x - 60) = 0\]\(x = 60\). Check: \(540 \div 60 = 9\) and \(540 \div 90 = 6\); \(9 - 6 = 3\).