How is total_score = total_score + score possible?

Question

I was thinking about question from mathematical point of view and it seems wrong. Can someone please explain the same

Answer 1

How do you think it is wrong?

Note that:
= is assignment operator and,
== is equality operator

total_score = total_score + score is right, but
total_score == total_score + score is definitely false (except when both of them are zero or score is zero)

Answer 2

Translate in in your head to:

'total_score shall henceforth carry the value total_score + score.'