Task №9

import pandas as pd
purchases = pd.read_csv('/datasets/returned.csv')
purchases['total'] = purchases['first'] + purchases['repeated']
purchases['repeated_share'] = purchases['repeated'] / purchases['total']
print(purchases.sort_values(by ='repeated_share', ascending=False))#сортировка по убыванию столбца доли повторных продаж к общим продажам