## Of course, I'm here to help! Let's break it down to understand the given expressions.

First, let's clarify the notation used:

The expression "115 cis 45Â°" represents a complex number. In this notation, "cis" stands for Cosine (cos) plus Sine (sin). So, "115 cis 45Â°" indicates a complex number with a magnitude of 115 and an angle of 45 degrees.

Now, let's look at the proposed solutions:

1. "115 cis 45Â°" - This is the original complex number given.

2. "115 cis 45Â° + 120Â°" - This expression adds 120Â° to the angle of the original complex number. So the result would be a new complex number with a magnitude of 115 and an angle of 45Â° + 120Â° = 165Â°.

3. "115 cis (45Â° + 120Â° + 120Â°)" - This expression adds 120Â° to the angle of the previous complex number (165Â°). So the result would be a new complex number with a magnitude of 115 and an angle of 45Â° + 120Â° + 120Â° = 285Â°.

Therefore, the three solutions provided are correct according to the given expressions.