A dealer sells a machine having marked price as Rs. 3840 at a discount of 20%. What is the selling price (in Rs.) of the machine?

The correct option is 3072.

Here is the step-by-step calculation to find the selling price of the machine:

1. Identify the given values:
Marked Price (MP) of the machine = Rs. 3840
Discount percentage = 20%

2. Calculate the discount amount:
The discount amount is calculated as 20% of the Marked Price:
$$\text{Discount Amount}=3840\times \frac{20}{100}$$

$$\text{Discount Amount}=3840\times 0.2=768$$
So, the discount offered on the machine is Rs. 768.

3. Calculate the Selling Price (SP):
The selling price is the marked price minus the discount amount:
$$\text{Selling Price (SP)}=\text{Marked Price (MP)}-\text{Discount Amount}$$

$$\text{Selling Price}=3840-768=3072$$

Alternatively, the selling price can be calculated directly as 80% (100% - 20%) of the marked price:
$$\text{Selling Price}=3840\times \frac{80}{100}=3840\times 0.8=3072$$

Therefore, the selling price of the machine is Rs. 3072.