If there is a + sign and a - sign in the problem which do I put

Maybe this will help

 

http://web2.0calc.com/questions/the-result-of-subtracting-a-negetive-integer-from-a-positive-integer-is-a-positve-integer#r1

You sometimes see an expression like: 21 + -7 you can write it as 21 - 7 and evaluate it that way.