The analysis process is as follows:

If the price of each piece is

Then the cost of buying 4 pieces before the discount is: 4a.

The cost of buying 4 pieces after discount is: 3a.

Equivalent to: 3a/4a* 100%=75%=7.5 fold.

Assuming that each dress costs 100 yuan, four dresses will be bought in 400 yuan without discount, and 300 yuan will be needed for discount. In fact, it takes three clothes to buy four clothes. That is, every piece of clothing actually only needs 75 yuan.

Extended data:

Discount calculation method:

1, original price × (discount10)

For example, the original price of 70 yuan is 30% off, that is, 70×(3÷ 10)=2 1.

For example, 20% discount means: original price × 20% discount.

2. Original price × discount/10

For example, the original price of 40 yuan is 50% off, that is, 40×5/ 10 =20.

3. Original price ×0. discount

For example, the original price 100 yuan, 10% discount, that is:100× 0.1=10.