Average acceleration is defined as
[tex]a = \frac{v_f - v_i}{t}[/tex]
here
[tex]v_f = final\: speed[/tex]
[tex]v_i = initial\: speed[/tex]
[tex]t = time [/tex]
now for x direction we can say
[tex]a_x = \frac{v_{2x} - v_{1x}}{t}[/tex]
[tex]a_x = \frac{-21.9 + 36.5}{9.97}[/tex]
[tex]a_x = 1.46 m/s^2[/tex]
Similarly for Y direction
[tex]a_y = \frac{v_{2y} - v_{1y}}{t}[/tex]
[tex]a_y = \frac{27.5 - 10.9}{9.97}[/tex]
[tex]a_y = 1.66 m/s^2[/tex]
so above is the acceleration in x and y directions