จำนวนเงินทั้งหมดที่ลูคัส มันชินี่ใช้ไปคือเท่าไร?
What is the total amount of money spent by Lucas Mancini?
invoices_df = pd.DataFrame(columns=['total', 'customer_id']); customers_df = pd.DataFrame(columns=['id', 'first_name', 'last_name'])
invoices_df.loc[invoices_df['customer_id'].isin(customers_df[(customers_df['first_name'] == 'Lucas') & (customers_df['last_name'] == 'Mancini')]['id']), 'total'].sum()