What is -65 - 15? i tried this on a calculator and it said -80. i am pretty sure that is wrong. the 65 is negative and the 15 is positive.

Nope its -80 

Change -65 - 15
Into        -65+ (-15)
See? Stay, Change, Change
Keep the first number, change the operation symbol and change the second number from positive to negative or negative to positive.(Flip the signs).

Example: $-65 in your bank account  PLUS another $-15= $-80
Even if the second number was positive, it would still be like this: $-65 MINUS +15 dollars= -80 because you took away 15 dollars. Get It? I hope so. No thanks needed, i am happy helping you and making you happy. Chat me or comment on my profile for more questions.