In a sample of 900 university students, all students are either freshmen or sophomores or junior or seniors, 24 percent are juniors and 72 percent are not sophomores. If there are 144 seniors, how many more freshmen than sophomores are there among the sample of students?

Explanation: m একটি integer হলে এটি odd বা even যেকোনটি হতে পারে, m কে odd ধরলে \((m-1)(m+2)-(m-1)(m-2) = (odd-1)(odd+2)-(odd-1)(odd-2) = (even \times odd)-(even \times odd) = even-even = even\) আবার, m -কে even ধরলে \((m-1)(m+2)-(m-1)(m-2) = (even-1)(even+2)-(even-1)(even-2) = (odd \times even)-(odd \times even) = even-even = even\) অর্থাৎ, যেকোন ভাবেই y এর মান even]