I will show you a method to find a velocity of anything:-
Find average velocity when acceleration is constant.
Set up an equation with position and time instead.
Find the distance between the start and end points.
Calculate the change in time.
Divide the total displacement by the total time.
Solve problems in two dimensions.
According to the formula you have given us to work with . . .
1). The airplane's acceleration is
(80 m/s north - zero) / (20 sec) = 4 m/sec^2 north
2). For the cyclist:
(V-final - zero) / 20sec = 0.5 m/s^2 south
Multiply each side by 20s : V-final = 0.5 m/s^2 south x (20sec) =
10 m/s south
