Marked price is same as the list price.

20% discount means that on Rs 100 (MP), the discount is Rs 20.

By unitary method, on Re 1 the discount will be Rs $\frac{20}{100}$

On Rs 220, discount = Rs $\frac{20}{100}$ x 220 = Rs 44

The sale price = (Rs 220 - Rs 44) or Rs 176

OR

A discount of 20% means for MP of Rs 100, the discount is Rs 20.

Hence, the sale price is Rs 80.

Using unitary method, when MP is Rs 100, sale price is Rs 80;

When MP is Re 1, sale price is Rs  $\frac{80}{100}$ 

Hence, when MP is Rs 220, sale price = Rs  $\frac{80}{100}$ x 220 = Rs 176.