Answer:
Vs/c = 20 [m/s]
Step-by-step explanation:
This is a problem of relative velocities, as velocity is a vector we can use addition or subtraction of vectors for the solution.
We are asked for the velocity of the sailboat with respect to an observer located in the canoe.
![V_(s/c)=V_(sailboat)-V_(canoe)\\V_(s/c)=15-(-5)\\V_(s/c)=20[m/s]](https://img.qammunity.org/2021/formulas/physics/college/nyykaxpq94galomxkeesct1018bywc3him.png)
Why is the speed of the canoe negative?, it is negative because the canoe moves in the opposite direction to the sailboat.