I wrote a simple script for adding that uses a function to hold two variables and then add them together. You create a function by using def and then giving it a name.

# -*- coding: utf-8 -*-

def add(value_1, value_2):
    print "Adding %d and %d together." % (value_1, value_2)
    return value_1 + value_2

cost = add(2345,1234)

print "The cost is: £{0:.2f}".format (cost)

Be sure to use the utf-8 value at the top or else Python will not understand the currency character.