After flying for 18 min in a wind blowing 42 km/h at an angle of `20^(@)` south of east, an airplane pilot is over a town that is 55 km due north of the starting point. What is the speed of the airplane relative to the air?

Explanation

To solve the problem, we need to find the speed of the airplane relative to the air, given the wind speed and direction, as well as the displacement of the airplane.

### Step-by-Step Solution:

1. **Understanding the Problem**:
- The airplane flies for 18 minutes (which we will convert to hours).
- The wind blows at 42 km/h at an angle of 20 degrees south of east.
- The airplane ends up 55 km due north of the starting point.
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