diy.py

with open(r"c:\Users\JUDY\Desktop\sales_list.txt","r",encoding="utf-8") as file:
    a=file.readlines()
final_sum=[]
for i in a:
    data=i.split()
    #print(data[1:])
    sum=0
    for sales in data[1:]:
        sum=sum+int(sales)
    result=data[0]+str(sum)+"\n"
    final_sum.append(result)
with open(r"c:\Users\JUDY\Desktop\saleslist.txt","a",encoding="utf-8") as file:
    file.writelines(final_sum)