Answer: 9+-1=8
Step-by-step explanation: With the - sign, the + sign cancels out because, a(9) is positive(+). Unless a(9) were to be negative (for example: -25 + -1 = -26), you subtract from the positives.
Think about: If you had just bought 10 bananas, & your neighbour wants to borrow 3 bananas, you don't go to the store to get 3 more. You have 10, so you let her borrow 3.