n= -15

n+(-7)-n=

Your second line makes no sense. n-7-n=-7

n+(-7)-n=

-15 + (-7) + 15 = -7

To simplify the given expression, let's break it down step by step.

Step 1: Write down the expression.
n + (-7) - n

Step 2: Simplify the expression by combining like terms.
In this case, the two terms with 'n' will cancel each other out because they have opposite signs. So, you are left with (-7).

Step 3: Final answer.
The expression simplified to -7.