solve 15-18+n and 18+5+N

nothing to solve. There is no equation.

Now, if you just want to simplify the expressions, you wind up with

-3+n and 23+N

-3 + n

23 + n

To simplify the expressions 15-18+n and 18+5+n, let's start by combining the like terms together.

For the expression 15-18+n:
1. Combine 15 and -18: 15-18 = -3.
2. The final simplified expression is -3 + n.

For the expression 18+5+n:
1. Combine 18 and 5: 18+5 = 23.
2. The final simplified expression is 23 + n.

So, the simplified expressions are -3 + n and 23 + n, respectively.