Ms. Sue, I apologize, but all I'm getting is answers, I need to know how to work them out myself as my teacher didn't make himself clear.
Here's your last problem.
-10 - (-7n) + (-9n)
You need to combine like terms.
- (-7n) + (-9n) are like terms.
How do you think they should be combined?
Remember that two negatives make a positive.