Alright, so the sum of two days is going to equal zero.
The variable here is what Jesse got on the first day. Let's call it "x".
x-6=0
x is the first day's score, -6 is the second day's score, and the total score is zero.
Now, add 6 to both sides.
x-6=0
+6 +6
x=6
Jesse's score for the first day was (+)6.
