Answer:
The rate of markdown it would have to offer is 27.3%.
Explanation:
The original price of sofa was, OP = $880.
The new price of sofa is, NP = $640
The change in price is:
![Change=OP-NP\\=880-640\\=240](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ag4bs2e9iu1x3l2nm3l378oq5o753v3elf.png)
The rate of markdown offered by the shopkeeper is:
![Rate\ of\ markdown=(Change\ in\ Price)/(Orignal\ Price)*100 \\=(240)/(880)*100\\ =0.27273*100\\\approx27.3\%](https://img.qammunity.org/2021/formulas/mathematics/middle-school/o3ncybf4fl3og8lnn5swjcsb68chz32wcn.png)
Thus, the rate of markdown offered by the shopkeeper is 27.3%.