import pandas as pd 
from openpyxl import load_workbook
from openpyxl.utils.dataframe import dataframe_to_rows

wb=load_workbook('regions.xlsx')
ws=wb.active
df=pd.read_excel('all_shifts.xlsx')

df1=df[['Sales Rep','Cost per','Units Sold']]
df1['Total'] = df1['Cost per'] * df1['Units Sold']
print(df1)

rows=dataframe_to_rows(df1,index=False)
for r_idx, row in enumerate(rows,1):
    for c_idx,col in enumerate(row,6):
        #print(col)
        ws.cell(row=r_idx,column=c_idx,value=col)

wb.save('combined.xlsx')