Python ValueError: too many values to unpack

You need to split on the comma:

score1,score2 = input ("Enter two scores separated by a comma:").split(",")

Note however that score1 and score2 will still be strings. You will need to convert them into numbers using either float or int (depending on what number type you want).

See an example:

>>> score1,score2 = input("Enter two scores separated by a comma:").split(",")
Enter two scores separated by a comma:1,2
>>> score1
'1'
>>> score1 = int(score1)
>>> score1
1
>>> score1 = float(score1)
>>> score1
1.0
>>>

1. You need to split the input you receive, because it arrives all in one string
2. Then, you'll need to convert them to numbers, because the term score1 + score2 will do string addition otherwise and you will get an error.