A lady has only 2

Let the no. of 25 - paisa coins be x.

the no of 50 - paisa coins = 50 - x

[∵ the total no. of coins = 50]

According to the question,

total money = Rs. 19.50 = 1950 paise

∴ 25x + 50(50 - x) = 1950

⇒ 2500 - 25x = 1950

⇒ 25x = 550

∴ x = 22

Thus, the no of 25 - paisa coins = x = 22 and,

the no of 50 - paisa coins = 50 - x = 50 - 22 = 28.