Correct Answer - Option 3 : 80

**Given **

Total number of coin = 120

Total amount = Rs 100

**Calculation **

Let the number of coins of 50 p and Re 1 be x and y

According to question

x + y = 120 ----(1)

x/2 + y = 100 ----(2)

Subtract equation (2)

By solving (1) and (2) from equation (1)

⇒ x - x/2 = 120 - 100

⇒ x/2 = 20

We get x = 40 and y = 80

So number of coins of Rs 1 = 80

**∴ The required answer is 80 **