Read one string, within that string we have numerical values also, then we have to display the sum of that numbers in that string.

Sure, here is a step by step solution in Python:

1. First, import the re module. This module provides support for regular expressions in Python.

import re

2. Read the string. For this example, let's assume the string is "abc123def456".

s = "abc123def456"

3. Use the re.findall() function to find all the numbers in the string. This function returns a list of all matches.

numbers = re.findall('\d+', s)

4. Convert the numbers from strings to integers using the map() function.

numbers = list(map(int, numbers))

5. Finally, use the sum() function to calculate the sum of the numbers.

total = sum(numbers)

6. Print the total.

print(total)

When you run this code, it will display the sum of the numbers in the string. In this case, the output will be 579 (which is 123 + 456).