Answer:
a = 6.87 [m/s²]
Step-by-step explanation:
To solve this problem we must use the following equation of kinematics.

where:
Vf = final velocity = 37 [m/s]
Vo = initial velocity = 15 [m/s]
a = acceleration [m/s²]
t = time = 3.2 [s]
Note: The positive sign in the above equation means that the velocity is increasing, due to the acceleration.
37 = 15 + a*3.2
3.2*a = 37 - 15
a = 6.87 [m/s²]