A jetliner, traveling northward, is landing with a speed of 72.4 m/s. Once the jet touches down, it has 806 m of runway in which to reduce its speed...

A jetliner, traveling northward, is landing with a speed of 72.4 m/s. Once the jet touches down, it has 806 m of runway in which to reduce its speed to 15.0 m/s. Compute the average acceleration (magnitude and direction) of the plane during landing (take the direction of the plane's motion as positive)...

How to do with steps and answer please.. need to learn fast