This is a kinematics problem.
Let's list out the kinematic formulas:
[tex]x= v_{i} t+at^2/2[/tex]
[tex]v_{f} ^2= v_{i} ^2+2ax[/tex]
[tex]v_{f} = v_{i} +at[/tex]
What do we know?
We have vi, vf, and x. We're trying to find acceleration. The formula that has all four of these is the second. Now, let's plug in and solve for a.
[tex]v_{f} ^2= v_{i} ^2+2ax[/tex]
[tex]220^2=450^2+2*.14*a[/tex]
[tex]-154100=.28*a[/tex]
[tex]a=-5.50*10^5 m/s^2[/tex]
