A boat has a velocity of 27.5 m/s [S30W]. 34 s later it had a velocity of 24.0 m/s [E66S]. What was its average acceleration?

Do a vector subtraction of the velocity vectors, and divide the result by 34 s.

V1 = -13.75i -23.82 j
V2 = -9.76i -21.93 j
V2 - V1 = +3.99i +1.89j
a = 0.117 i + 0.0556 j
|a| = 0.130 m/s^2
The ratio of j (north) and i (east) components will tell you the direction