Question 8186
You can start by considering the amount Ramon owes as a negative balance and any credits he receives or payments he makes as positive amounts to his balance..
Starting with his initial balance of -$780.00, and adding all of the credits/payments and subtracting the purchases, we get:

-$780.00 + $43.10 + 36.80 + $125.00 + $400.00 - $82.75 Simplifying, we get:
-$862.75 + $604.90 = -$257.85

So Ramon still owes: $ 257.85 

This is different from your answer, so you might want to double-check your addition.