The acceleration of the object due to unbalanced force can be given as,
[tex]a=\frac{F}{m}[/tex]Substitute the known values,
[tex]\begin{gathered} a=\frac{-20.0\text{ N}}{3.75\text{ kg}}(\frac{1kgm/s^2}{1\text{ N}}) \\ =-5.33m/s^2 \end{gathered}[/tex]Thus, the acceleration of the object is -5.33 m/s^2.