Diagram
A = ship's starting point and the location of the Columbia Bar
B = ship's location 2 hours after leaving point A
C = ship's location 3 hours after leaving point B
D = point used to set up bearing of S30W
1 knot = 1 nautical mile per hour
15 knots = 15 nautical miles per hour
After 2 hours, the ship travels a distance of 2*15 = 30 nautical miles. So AB = 30.
Similarly, BC = 45 since 3*15 = 45
Angle DAB = 30 degrees. We start by facing directly south, then turn 30 degrees westward, which is what the notation "S30W" indicates.
For more information and examples about compass bearings, see this page.
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For now, ignore point D. Focus solely on triangle ABC.
Triangle ABC is a right triangle with the 90 degree angle at point B. This is due to the fact that the ship turns 90 degrees to the southeast.
tan(angle) = opposite/adjacent
tan(A) = BC/AB
tan(A) = 45/30
tan(A) = 1.5
A = arctan(1.5)
A = 56.3099324740202 You need to make sure your calculator is in degree mode
So angle BAC is roughly 56.3099324740202 degrees
Subtract off the green angle 30 degrees to get
(angle BAC) - (angle DAB) = 56.3099324740202 - 30 = 26.3099324740202
which is the approximate measure of the red angle DAC.
If we're situated at point A, face directly south, and turn roughly 26.3099324740202 degrees eastward, then we'll be looking directly at point C.
Rounding to 4 decimal places, that would be roughly 26.3099; feel free to change the level of accuracy based off what your teacher instructs.
The bearing to the ship from the Columbia Bar is approximately S 26.3099 E