In order to add two numbers, we are using arithmetic operator + in python. If the numbers you are using in addition are coming from input function, first, you need to convert them to float or integer like in the example below:

firstnumber = 1.5
secondnumber= 6.3
total = float(firstnumber) + int(secondnumber)
print('The sum of {0} and {1} is {2}'.format(firstnumber, secondnumber, total))