Answer:
The distance between the yacht from the ship is about 33.6 km. 
Step-by-step explanation:
The diagram is attached below. 
Point A is the shipe, Point B is the tugboat, and Point C is the yacht. 
Since the tugboat is 28 km away, and the scale being used is 1 cm : 4 km, the tugboat is 7 cm away from the ship at a 210° bearing on the diagram. 
Likewise, the yacht is 6 cm away from the tugboat at a 210° bearing. 
To find the distance between the yacht to the ship, we need to determine the value of <em>x</em>. 
To do so, we can use the Law of Cosines:

First, we need to determine ∠B. 
A has a bearing of 210°. 180° is covered by QI and IV. So, the small angle in QIII is 30°. 
By Alternate Interior Angles, the angle in QI (inside the triangle) of Point B must also be 30°. 
And since Point B has a bearing of 310°, 270° is covered in total by QI, QIV, and QIII. So, 40° is left in QII. 
Therefore, 50° is the measure of the angle in QIII within the triangle of Point B. 
Thus, ∠B measures 50° + 30° = 80°. 
So, ∠B measures 80°. We also know that <em>a</em> = 6 and <em>c</em> = 7. Substitute: 

Simplify and take the square root of both sides. So: 

Approximate using a calculator: 

Since 1 cm : 4km, to find the distance in km, we simply need to multiply by four. So: 

The distance between the yacht from the ship is about 33.6 km.