Let the number of Rs. 50 and Rs. 100 notes be ‘a’ and ‘b’

Given, Meena went to a bank to withdraw Rs 2000. She asked the cashier to give her Rs 50 and Rs 100 notes only. Meena got 25 notes in all.

⇒ 50a + 100b = 2000

⇒ a + 2b = 40 ------- (1)

Also, a + b = 25 ----- (2)

(1) – (2)

⇒ b = 15

Thus, a = 10