Recall that for constant acceleration, we have
[tex]{v_f}^2-{v_i}^2=2a\Delta x[/tex]
where [tex]v_f[/tex] is the car's final velocity, [tex]v_i[/tex] is its initial velocity, [tex]a[/tex] is its acceleration, and [tex]\Delta x[/tex] is its displacement. Plugging everything we know into this equation gives
[tex]\left(-10.9\dfrac{\rm m}{\rm s}\right)^2-\left(-27.7\dfrac{\rm m}{\rm s}\right)^2=2a\left(-105\,\mathrm m\right)[/tex]
[tex]\implies\boxed{a=3.09\dfrac{\rm m}{\mathrm s^2}}[/tex]
