Sum of strings extracted from text file using regex

Question

I am just learning python and need some help for my class assignment.

I have a file with text and numbers in it. Some lines have from one to three numbers and other

Answer 1

import re

fl=open('regex_sum_7469.txt')
ls=[]

for x in fl: #create a list in the list
   x=x.rstrip()
   print x
   t= re.findall('[0-9]+',x) #all numbers
   for d in t: #for loop as there a empthy values in the list a
        ls.append(int(d))
print (sum(ls))